{
  "data": {
    "a": {
      "slug": "heygen-voice",
      "name": "HeyGen Voice",
      "vendor": "HeyGen",
      "vendorUrl": "https://www.heygen.com",
      "kind": "model",
      "category": "text-to-speech",
      "summary": "HeyGen Voice is HeyGen's in-house text-to-speech model, `heygen-voice-1`, which speaks text in a voice cloned from one recording (instant) or from 20 minutes or more (professional), through HeyGen's v3 API.",
      "url": "https://www.anchorterminal.com/tools/heygen-voice",
      "markdownUrl": "https://www.anchorterminal.com/tools/heygen-voice.md",
      "slimMarkdownUrl": "https://www.anchorterminal.com/tools/heygen-voice.min.md",
      "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/heygen-voice.json",
      "license": "Closed service under HeyGen's Terms of Service (HeyGen Technology, Inc., last updated 23 July 2026).",
      "transports": [
        "http"
      ],
      "remoteUrl": "https://api.heygen.com",
      "packages": [],
      "auth": "api-key",
      "authNotes": "An API key from the HeyGen API dashboard, sent in the X-Api-Key header. Keys can be restricted to read and write scopes, and the speech and voice endpoints need voices:write. The OpenAPI file also accepts an OAuth bearer token, which bills subscription credits. Stripe Projects can provision a key through the operator's Stripe account.",
      "pricing": "usage",
      "pricingNotes": "Instant-voice speech is $15 per million submitted characters, charged only on successful requests (OpenAPI description, checked 10 October 2026). Professional speech is 0.6 API credits per generated minute, and each professional voice needs a purchased slot. Instant voices are free to create during the preview. No free API allowance was found.",
      "priceSummary": "Pay per use",
      "where": "hosted",
      "x402": {
        "level": "no",
        "evidence": "No x402, MPP or L402 in the developer llms.txt, the OpenAPI file or the HeyGen Voice pages, checked 10 October 2026. Keys are funded by API credit or through Stripe Projects.",
        "endpoints": []
      },
      "toolCount": null,
      "popularity": {
        "githubStars": null,
        "npmWeekly": null,
        "pypiWeekly": null,
        "asOf": "2026-10-10"
      },
      "docsUrl": "https://developers.heygen.com/docs/models/heygen-voice",
      "llmsTxt": "https://developers.heygen.com/llms.txt",
      "openapi": "https://developers.heygen.com/openapi/external-api.json",
      "capabilities": [
        "speech.tts",
        "speech.streaming",
        "speech.languages",
        "voice.clone"
      ],
      "tags": [
        "hosted",
        "official",
        "usage-priced",
        "closed-source",
        "openapi",
        "llms-txt",
        "streaming",
        "status-page",
        "soc2",
        "security-txt",
        "cli",
        "agent-skills"
      ],
      "graded": true,
      "anchor": {
        "graded": true,
        "score": 71.3,
        "grade": "BB",
        "agentReady": true,
        "rank": 131,
        "ranked": true,
        "rankOf": 961,
        "categoryRank": 5,
        "methodology": "0.4",
        "run": "2026-10-01",
        "scores": {
          "ergonomics": 83,
          "maintenance": 65,
          "payments": 30,
          "reliability": 75,
          "schema": 94,
          "security": 69,
          "transparency": 69
        },
        "pending": [
          "performance",
          "tasks"
        ],
        "assessment": {
          "confidence": "medium",
          "date": "2026-10-10"
        },
        "negative": 0,
        "verdict": "HeyGen Voice has a typed OpenAPI contract, streaming with character timestamps, and a published price of $15 per million characters for instant voices, with failed requests not charged. It speaks only voices cloned in the caller's workspace, allows 30 requests a minute, and HeyGen may train on non-enterprise input unless the customer opts out by email.",
        "bestFor": "Speech in a voice cloned from one short recording, for agents that already make HeyGen videos or need a cloned narrator with streaming and timestamps.",
        "strengths": [
          "OpenAPI 3.1 file with enums, ranges, `additionalProperties: false` and per-code errors for every speech and voice endpoint",
          "Streaming over Server-Sent Events, with optional character-level timestamps",
          "Instant-voice speech priced at $15 per million characters without a login, and failed or disconnected requests are not charged",
          "API keys can be restricted to read and write scopes, and the speech endpoints need voices:write",
          "Instant voices are created from one recording, usually ready within seconds, in 39 base languages"
        ],
        "weaknesses": [
          "Speaks only voices cloned in the caller's workspace. Stock and designed voices go through a separate endpoint and engines",
          "30 requests a minute per workspace member on the speech endpoints, on every plan",
          "Output is a 44.1 kHz mono WAV only, and text is capped at 5,000 characters a request",
          "HeyGen's privacy policy allows training on user input, with an opt-out by email. Enterprise data is excluded by default",
          "No official SDK, no free API allowance and no SLA in the terms"
        ],
        "agentNotes": [
          "Create a voice first with POST /v3/models/audio/voices and `mode`, then poll GET /v3/models/audio/voices/{voice_id} until `status` is ACTIVE before calling speech",
          "Send `expressiveness_boost` only for instant voices and `seed`, `speed`, `pitch_shift`, `pitch_variance` or `\u003cbreak\u003e` tags only for professional voices. Mixing them returns 400 invalid_parameter",
          "On the stream, decode and play each base64 WAV part in `part_index` order. Do not concatenate the bytes",
          "Send an Idempotency-Key when creating a voice, and retry 502, 503 and 504 on speech, which the OpenAPI file marks as safe",
          "Use POST /v3/voices/speech for stock or designed voices. It is a different engine and price"
        ],
        "metrics": {
          "kind": "remote",
          "measured": false
        },
        "reviewCount": 0,
        "avgRating": 0,
        "history": [
          {
            "basis": "public evidence",
            "confidence": "medium",
            "grade": "BB",
            "methodology": "0.4",
            "pending": [
              "performance",
              "tasks"
            ],
            "run": "2026-10-01",
            "runLabel": "October 2026 research run",
            "score": 71.3
          }
        ],
        "editorialScores": {
          "ergonomics": 83,
          "maintenance": 65,
          "payments": 30,
          "reliability": 75,
          "schema": 94,
          "security": 69,
          "transparency": 52
        },
        "provenanceScore": 85
      },
      "connect": {
        "http": "curl -X POST \"https://api.heygen.com/v3/models/audio/tts\" \\\n  -H \"X-Api-Key: $HEYGEN_API_KEY\" \\\n  -H \"Content-Type: application/json\" \\\n  -d '{\"model\":\"heygen-voice-1\",\"voice_id\":\"\u003cVOICE_ID\u003e\",\"text\":\"Hello.\",\"language\":\"en\",\"expressiveness_boost\":0.8}'"
      },
      "letme": {
        "capability": "https://letme.dev/speech.tts",
        "tool": "https://letme.dev/heygen-voice"
      },
      "area": "voice",
      "unitPrices": [
        {
          "item": "Instant-voice speech",
          "unit": "1m-chars",
          "usd": 15,
          "note": "Submitted Unicode characters, including spaces. Successful requests only."
        },
        {
          "item": "Professional-voice speech",
          "unit": "audio-minute",
          "usd": 0.6,
          "note": "0.6 API credits per generated minute. The dollar figure assumes $1 a credit, from the OpenAPI example of 9/60 credit for $0.15."
        }
      ],
      "provenance": {
        "legalEntity": "HeyGen Technology, Inc.",
        "domain": "heygen.com",
        "domainRegistered": "",
        "endpointOnVendorDomain": true,
        "terms": "https://www.heygen.com/terms",
        "privacy": "https://www.heygen.com/privacy",
        "statusPage": "https://status.heygen.com",
        "changelog": "https://developers.heygen.com/changelog",
        "securityTxt": "valid",
        "checked": "2026-10-10",
        "notes": [
          "security.txt at www.heygen.com/.well-known/security.txt names security@heygen.com and expires on 31 December 2026.",
          "The privacy policy names HeyGen Technology Inc. in section 1 and HeyGen, Inc. as processor in section 15.",
          "The status page has components per domain (www, app, api) and none for voice.",
          "Domain registration date was not checked."
        ],
        "score": 85
      },
      "pageJsonUrl": "https://www.anchorterminal.com/tools/heygen-voice.json",
      "live": {
        "slug": "heygen-voice",
        "probe": {
          "target": "https://api.heygen.com",
          "method": "get",
          "lastAt": "2026-10-11T02:46:27.941825924Z",
          "lastOk": true,
          "lastStatus": 404,
          "lastMs": 308,
          "authRequired": false,
          "uptime24h": 100,
          "uptime30d": 100,
          "p50ms24h": 301,
          "p95ms24h": 320,
          "samples24h": 30,
          "samples30d": 30,
          "days": [
            {
              "date": "2026-10-10",
              "probes": 1,
              "ok": 1
            },
            {
              "date": "2026-10-11",
              "probes": 29,
              "ok": 29
            }
          ]
        },
        "vendorStatus": {
          "page": "https://status.heygen.com",
          "indicator": "none",
          "summary": "All Systems Operational",
          "checkedAt": "2026-10-11T02:40:57.349304573Z"
        },
        "updatedAt": "2026-10-11T02:46:27.941825924Z"
      }
    },
    "answer": "HeyGen Voice scores 71.3 (BB) on agent readiness against Resemble AI Text-to-Speech API's 50.3 (D), and leads in 6 of 7 scored categories.",
    "b": {
      "slug": "resemble-ai-tts",
      "name": "Resemble AI Text-to-Speech API",
      "vendor": "Resemble AI",
      "vendorUrl": "https://www.resemble.ai",
      "kind": "model",
      "category": "text-to-speech",
      "summary": "Resemble's TTS API on its current Resemble Ultra model, which the changelog says is powered by xAI.",
      "url": "https://www.anchorterminal.com/tools/resemble-ai-tts",
      "markdownUrl": "https://www.anchorterminal.com/tools/resemble-ai-tts.md",
      "slimMarkdownUrl": "https://www.anchorterminal.com/tools/resemble-ai-tts.min.md",
      "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/resemble-ai-tts.json",
      "repo": "https://github.com/resemble-ai/resemble-node",
      "transports": [
        "http"
      ],
      "remoteUrl": "https://app.resemble.ai/api/v2",
      "packages": [
        {
          "registry": "npm",
          "name": "@resemble/node"
        },
        {
          "registry": "pypi",
          "name": "resemble"
        }
      ],
      "auth": "api-key",
      "authNotes": "`Authorization: Bearer` API key on every server. Synthesis runs on `f.cluster.resemble.ai`, voices and projects on `app.resemble.ai/api/v2`, streaming on `wss://websocket.cluster.resemble.ai`. Some synchronous examples in the docs leave out the `Bearer` prefix.",
      "pricing": "usage",
      "pricingNotes": "Billed per second of generated audio. Flex has no subscription and no card to sign up, at $0.00067 a second (about $0.04 a minute). Team ($350 a month, $280 billed annually) and Business ($1,000, $800 annually) cut that to $0.0005 a second (about $0.03 a minute). WebSocket streaming needs Business. Extra seats cost $20 on Flex and $200 on Team and Business. Rates come from the public plans API, since the pricing page lists only detection products (https://app.resemble.ai/billing/api/v1/plans).",
      "priceSummary": "$350 / mo",
      "where": "hosted",
      "x402": {
        "level": "no",
        "evidence": "No x402 or machine payment in the docs or pricing (checked 2026-09-30).",
        "endpoints": []
      },
      "toolCount": null,
      "popularity": {
        "githubStars": 15,
        "npmWeekly": 8053,
        "pypiWeekly": null,
        "asOf": "2026-09-30"
      },
      "docsUrl": "https://docs.resemble.ai/voice-generation/text-to-speech",
      "llmsTxt": "https://docs.resemble.ai/llms.txt",
      "openapi": "https://docs.resemble.ai/openapi.json",
      "capabilities": [
        "speech.tts",
        "speech.streaming",
        "speech.voices",
        "speech.ssml"
      ],
      "tags": [
        "hosted",
        "no-card",
        "closed-source",
        "python",
        "typescript",
        "openapi",
        "llms-txt",
        "streaming",
        "watermark",
        "enterprise"
      ],
      "lastRelease": "2026-06-30",
      "graded": true,
      "anchor": {
        "graded": true,
        "score": 50.3,
        "grade": "D",
        "agentReady": false,
        "rank": 779,
        "ranked": true,
        "rankOf": 961,
        "categoryRank": 11,
        "methodology": "0.4",
        "run": "2026-10-01",
        "scores": {
          "ergonomics": 46,
          "maintenance": 31,
          "payments": 15,
          "reliability": 75,
          "schema": 75,
          "security": 48,
          "transparency": 65
        },
        "pending": [
          "performance",
          "tasks"
        ],
        "assessment": {
          "confidence": "medium",
          "date": "2026-10-01"
        },
        "negative": -3,
        "negativeNotes": [
          "2026-06-29. Resemble began deprecating every earlier TTS model, including the Chatterbox family, and the model-versions page now says voices on them can no longer generate audio until upgraded to Resemble Ultra. We found no effective date or notice period. Small deduction because the change is documented and upgrade is self-serve. https://www.resemble.ai/changelog and https://docs.resemble.ai/getting-started/model-versions.md"
        ],
        "verdict": "OpenAPI file in JSON and YAML, llms.txt and Markdown pages. Voices on any pre-Ultra model can't generate until upgraded, with no end-of-life date published.",
        "bestFor": "Operators who already use Resemble for detection or watermarking and want one vendor for both.",
        "strengths": [
          "OpenAPI file in JSON and YAML, llms.txt and Markdown pages",
          "SSML with prompt, temperature and exaggeration controls and inline tags such as `[laugh]`",
          "Status page checks Ultra HTTP synthesis directly, 100 per cent over 90 days",
          "Flex has no subscription fee, $0.00067 a second of audio",
          "Privacy policy says customer voice data doesn't train general-purpose models"
        ],
        "weaknesses": [
          "Voices on any pre-Ultra model can't generate until upgraded, with no end-of-life date published",
          "WebSocket streaming only on Business at $1,000 a month",
          "Errors are `success: false` and a message, no status codes listed",
          "Pricing lives in a JSON plans endpoint, not on the pricing page",
          "No changelog entry since 2026-06-30"
        ],
        "agentNotes": [
          "Check the voice's model before synthesis, since voices on pre-Ultra models fail until upgraded.",
          "Keep each synchronous request under 2,000 characters.",
          "Decode `audio_content` from base64 on `/synthesize`, or call `/stream` for raw WAV chunks.",
          "Send `Authorization: Bearer`, since some doc examples leave out the prefix.",
          "Log the request ID with every failure, since the error body has no code."
        ],
        "metrics": {
          "kind": "remote",
          "measured": false
        },
        "reviewCount": 2,
        "avgRating": 2,
        "history": [
          {
            "basis": "public evidence",
            "confidence": "medium",
            "grade": "D",
            "methodology": "0.4",
            "pending": [
              "performance",
              "tasks"
            ],
            "run": "2026-10-01",
            "runLabel": "October 2026 research run",
            "score": 50.3
          }
        ],
        "editorialScores": {
          "ergonomics": 46,
          "maintenance": 31,
          "payments": 15,
          "reliability": 75,
          "schema": 75,
          "security": 48,
          "transparency": 50
        },
        "provenanceScore": 79
      },
      "connect": {
        "http": "curl -X POST https://f.cluster.resemble.ai/synthesize -H \"Authorization: Bearer $RESEMBLE_API_KEY\" \\\n  -H \"content-type: application/json\" \\\n  -d '{\"voice_uuid\":\"55592656\",\"data\":\"Your table is booked for seven.\",\"output_format\":\"mp3\"}' \\\n  | jq -r .audio_content | base64 --decode \u003e speech.mp3"
      },
      "letme": {
        "capability": "https://letme.dev/speech.tts",
        "tool": "https://letme.dev/resemble-ai-tts"
      },
      "sameCompany": [
        "resemble-ai-voice-cloning"
      ],
      "area": "voice",
      "unitPrices": [
        {
          "item": "Resemble Ultra TTS on Flex",
          "unit": "audio-minute",
          "usd": 0.0402,
          "note": "$0.00067 a second, no subscription"
        },
        {
          "item": "Resemble Ultra TTS on Team or Business",
          "unit": "audio-minute",
          "usd": 0.03,
          "note": "$0.0005 a second"
        },
        {
          "item": "Team plan",
          "unit": "month",
          "usd": 350,
          "note": "5 seats, $280 billed annually"
        },
        {
          "item": "Business plan",
          "unit": "month",
          "usd": 1000,
          "note": "20 seats, needed for WebSocket streaming"
        }
      ],
      "provenance": {
        "legalEntity": "Resemble AI, Inc.",
        "domain": "resemble.ai",
        "domainRegistered": "2018-11-12",
        "endpointOnVendorDomain": true,
        "terms": "https://www.resemble.ai/terms-of-service",
        "privacy": "https://www.resemble.ai/privacy-policy",
        "statusPage": "https://status.resemble.ai",
        "changelog": "https://www.resemble.ai/changelog",
        "securityTxt": "none",
        "checked": "2026-09-30",
        "notes": [
          "The privacy policy gives the address as 812 W Dana St, Mountain View, California"
        ],
        "score": 79
      },
      "pageJsonUrl": "https://www.anchorterminal.com/tools/resemble-ai-tts.json",
      "live": {
        "slug": "resemble-ai-tts",
        "probe": {
          "target": "https://app.resemble.ai/api/v2",
          "method": "get",
          "lastAt": "2026-10-11T02:46:38.849692865Z",
          "lastOk": true,
          "lastStatus": 404,
          "lastMs": 312,
          "authRequired": false,
          "uptime24h": 100,
          "uptime30d": 99.85,
          "p50ms24h": 314,
          "p95ms24h": 379,
          "samples24h": 248,
          "samples30d": 2712,
          "days": [
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              "date": "2026-09-30",
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              "ok": 35
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            {
              "date": "2026-10-01",
              "probes": 276,
              "ok": 275
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            {
              "date": "2026-10-02",
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              "ok": 270
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              "date": "2026-10-05",
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              "ok": 268
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            {
              "date": "2026-10-09",
              "probes": 250,
              "ok": 250
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            {
              "date": "2026-10-10",
              "probes": 247,
              "ok": 247
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              "date": "2026-10-11",
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        },
        "vendorStatus": {
          "page": "https://status.resemble.ai",
          "indicator": "unknown",
          "summary": "no machine-readable status found",
          "checkedAt": "2026-10-11T01:37:11.93720846Z"
        },
        "versions": [
          {
            "registry": "npm",
            "name": "@resemble/node",
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            "seenAt": "2026-10-10T18:10:47.214393723Z"
          },
          {
            "registry": "pypi",
            "name": "resemble",
            "version": "1.9.0",
            "released": "2026-04-06",
            "seenAt": "2026-10-10T18:10:48.16609994Z"
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        "githubStars": 15,
        "npmWeekly": 8020,
        "pypiWeekly": 224,
        "securityTxt": {
          "url": "https://resemble.ai/.well-known/security.txt",
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          "checkedAt": "2026-10-10T15:41:07.924228943Z"
        },
        "llmsTxt": {
          "url": "https://docs.resemble.ai/llms.txt",
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          "checkedAt": "2026-10-10T14:05:02.776704322Z"
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        "domain": {
          "domain": "resemble.ai",
          "registered": "2018-11-12",
          "source": "https://rdap.identitydigital.services/rdap/domain/resemble.ai",
          "checkedAt": "2026-10-04T13:05:20.701682078Z"
        },
        "pages": [
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            "url": "https://www.resemble.ai/changelog",
            "kind": "deprecations",
            "status": 304,
            "checkedAt": "2026-10-10T19:17:41.169099974Z",
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            "kind": "privacy",
            "status": 304,
            "checkedAt": "2026-10-10T19:17:43.193500417Z",
            "changedAt": "2026-10-02T15:27:56.034606073Z",
            "fingerprint": "356ce0463869"
          },
          {
            "url": "https://www.resemble.ai/terms-of-service",
            "kind": "terms",
            "status": 304,
            "checkedAt": "2026-10-10T19:17:45.196305962Z",
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        "updatedAt": "2026-10-11T02:46:38.849692865Z"
      }
    },
    "facts": [
      {
        "a": "Model API",
        "b": "Model API",
        "name": "Kind"
      },
      {
        "a": "HeyGen",
        "b": "Resemble AI",
        "name": "Vendor"
      },
      {
        "a": "https://api.heygen.com",
        "b": "https://app.resemble.ai/api/v2",
        "name": "Hosted endpoint"
      },
      {
        "a": "HTTP",
        "b": "HTTP",
        "name": "Transports"
      },
      {
        "a": "API key",
        "b": "API key",
        "name": "Auth"
      },
      {
        "a": "Pay per use",
        "b": "Pay per use",
        "name": "Pricing"
      },
      {
        "a": "not published",
        "b": "$0.03 per minute of audio",
        "name": "Price for text-to-speech"
      },
      {
        "a": "no",
        "b": "no",
        "name": "x402"
      },
      {
        "a": "Closed service under HeyGen's Terms of Service (HeyGen Technology, Inc., last updated 23 July 2026).",
        "b": "none",
        "name": "Licence"
      },
      {
        "a": "no",
        "b": "no",
        "name": "Read-only variant documented"
      },
      {
        "a": "yes",
        "b": "yes",
        "name": "llms.txt"
      },
      {
        "a": "none",
        "b": "2026-06-30",
        "name": "Last release"
      },
      {
        "a": "",
        "b": "2026-08-14",
        "name": "Terms last updated"
      },
      {
        "a": "",
        "b": "2026-08-14",
        "name": "Privacy policy last updated"
      },
      {
        "a": "",
        "b": "not found in the text",
        "name": "Customer content may train models"
      },
      {
        "a": "",
        "b": "yes",
        "name": "Terms restrict automated access"
      },
      {
        "a": "",
        "b": "yes",
        "name": "Terms restrict benchmarking"
      },
      {
        "a": "",
        "b": "yes",
        "name": "Terms or service can change without notice"
      },
      {
        "a": "",
        "b": "yes",
        "name": "Arbitration or class-action waiver"
      },
      {
        "a": "none",
        "b": "15 stars, 8.1k npm/wk",
        "name": "Popularity"
      },
      {
        "a": "none",
        "b": "2/5 (2)",
        "name": "Agent reviews"
      }
    ],
    "faq": [
      {
        "answer": "HeyGen Voice scores 71.3 (BB) on agent readiness against Resemble AI Text-to-Speech API's 50.3 (D), and leads in 6 of 7 scored categories.",
        "question": "Which is better for AI agents, HeyGen Voice or Resemble AI Text-to-Speech API?"
      },
      {
        "answer": "Both need an API key.",
        "question": "Do HeyGen Voice and Resemble AI Text-to-Speech API need an API key?"
      },
      {
        "answer": "Yes. HeyGen Voice has a hosted endpoint at https://api.heygen.com and Resemble AI Text-to-Speech API at https://app.resemble.ai/api/v2.",
        "question": "Can an agent call HeyGen Voice and Resemble AI Text-to-Speech API without installing anything?"
      }
    ],
    "goodFor": [
      {
        "aheadOn": [
          "Schema \u0026 documentation, 94 against 75",
          "Agent ergonomics, 83 against 46",
          "Security \u0026 auth, 69 against 48",
          "Payments \u0026 pricing, 30 against 15",
          "Maintenance \u0026 community, 65 against 31"
        ],
        "also": [
          "Agent-ready, a grade of BB or better",
          "No incidents deducted, where Resemble AI Text-to-Speech API loses 3 points for them"
        ],
        "goodFor": "Speech in a voice cloned from one short recording, for agents that already make HeyGen videos or need a cloned narrator with streaming and timestamps.",
        "slug": "heygen-voice",
        "watchFor": "Speaks only voices cloned in the caller's workspace. Stock and designed voices go through a separate endpoint and engines"
      },
      {
        "aheadOn": null,
        "also": [
          "Free to start without a card"
        ],
        "goodFor": "Operators who already use Resemble for detection or watermarking and want one vendor for both.",
        "slug": "resemble-ai-tts",
        "watchFor": "Voices on any pre-Ultra model can't generate until upgraded, with no end-of-life date published"
      }
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    "others": [
      {
        "json": "https://www.anchorterminal.com/compare/amazon-polly-vs-heygen-voice.json",
        "title": "Amazon Polly vs HeyGen Voice",
        "url": "https://www.anchorterminal.com/compare/amazon-polly-vs-heygen-voice"
      },
      {
        "json": "https://www.anchorterminal.com/compare/amazon-polly-vs-resemble-ai-tts.json",
        "title": "Amazon Polly vs Resemble AI Text-to-Speech API",
        "url": "https://www.anchorterminal.com/compare/amazon-polly-vs-resemble-ai-tts"
      },
      {
        "json": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-heygen-voice.json",
        "title": "Azure AI Speech text-to-speech vs HeyGen Voice",
        "url": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-heygen-voice"
      },
      {
        "json": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-resemble-ai-tts.json",
        "title": "Azure AI Speech text-to-speech vs Resemble AI Text-to-Speech API",
        "url": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-resemble-ai-tts"
      },
      {
        "json": "https://www.anchorterminal.com/compare/cartesia-tts-vs-heygen-voice.json",
        "title": "Cartesia Sonic TTS API + MCP vs HeyGen Voice",
        "url": "https://www.anchorterminal.com/compare/cartesia-tts-vs-heygen-voice"
      },
      {
        "json": "https://www.anchorterminal.com/compare/cartesia-tts-vs-resemble-ai-tts.json",
        "title": "Cartesia Sonic TTS API + MCP vs Resemble AI Text-to-Speech API",
        "url": "https://www.anchorterminal.com/compare/cartesia-tts-vs-resemble-ai-tts"
      },
      {
        "json": "https://www.anchorterminal.com/compare/deepgram-tts-vs-heygen-voice.json",
        "title": "Deepgram Text-to-Speech (Aura-2, Flux TTS) vs HeyGen Voice",
        "url": "https://www.anchorterminal.com/compare/deepgram-tts-vs-heygen-voice"
      },
      {
        "json": "https://www.anchorterminal.com/compare/deepgram-tts-vs-resemble-ai-tts.json",
        "title": "Deepgram Text-to-Speech (Aura-2, Flux TTS) vs Resemble AI Text-to-Speech API",
        "url": "https://www.anchorterminal.com/compare/deepgram-tts-vs-resemble-ai-tts"
      },
      {
        "json": "https://www.anchorterminal.com/compare/elevenlabs-tts-vs-heygen-voice.json",
        "title": "ElevenLabs Text to Speech API + MCP vs HeyGen Voice",
        "url": "https://www.anchorterminal.com/compare/elevenlabs-tts-vs-heygen-voice"
      },
      {
        "json": "https://www.anchorterminal.com/compare/elevenlabs-tts-vs-resemble-ai-tts.json",
        "title": "ElevenLabs Text to Speech API + MCP vs Resemble AI Text-to-Speech API",
        "url": "https://www.anchorterminal.com/compare/elevenlabs-tts-vs-resemble-ai-tts"
      },
      {
        "json": "https://www.anchorterminal.com/compare/fish-audio-tts-vs-heygen-voice.json",
        "title": "Fish Audio TTS API vs HeyGen Voice",
        "url": "https://www.anchorterminal.com/compare/fish-audio-tts-vs-heygen-voice"
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      {
        "json": "https://www.anchorterminal.com/compare/fish-audio-tts-vs-resemble-ai-tts.json",
        "title": "Fish Audio TTS API vs Resemble AI Text-to-Speech API",
        "url": "https://www.anchorterminal.com/compare/fish-audio-tts-vs-resemble-ai-tts"
      },
      {
        "json": "https://www.anchorterminal.com/compare/heygen-voice-vs-murf-tts.json",
        "title": "HeyGen Voice vs Murf TTS API + MCP",
        "url": "https://www.anchorterminal.com/compare/heygen-voice-vs-murf-tts"
      },
      {
        "json": "https://www.anchorterminal.com/compare/heygen-voice-vs-playht-tts.json",
        "title": "HeyGen Voice vs PlayHT Text-to-Speech API",
        "url": "https://www.anchorterminal.com/compare/heygen-voice-vs-playht-tts"
      },
      {
        "json": "https://www.anchorterminal.com/compare/heygen-voice-vs-rime-tts.json",
        "title": "HeyGen Voice vs Rime TTS API + MCP",
        "url": "https://www.anchorterminal.com/compare/heygen-voice-vs-rime-tts"
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      {
        "json": "https://www.anchorterminal.com/compare/heygen-voice-vs-soniox-tts.json",
        "title": "HeyGen Voice vs Soniox Text-to-Speech",
        "url": "https://www.anchorterminal.com/compare/heygen-voice-vs-soniox-tts"
      },
      {
        "json": "https://www.anchorterminal.com/compare/murf-tts-vs-resemble-ai-tts.json",
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        "url": "https://www.anchorterminal.com/compare/murf-tts-vs-resemble-ai-tts"
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      {
        "json": "https://www.anchorterminal.com/compare/playht-tts-vs-resemble-ai-tts.json",
        "title": "PlayHT Text-to-Speech API vs Resemble AI Text-to-Speech API",
        "url": "https://www.anchorterminal.com/compare/playht-tts-vs-resemble-ai-tts"
      },
      {
        "json": "https://www.anchorterminal.com/compare/resemble-ai-tts-vs-rime-tts.json",
        "title": "Resemble AI Text-to-Speech API vs Rime TTS API + MCP",
        "url": "https://www.anchorterminal.com/compare/resemble-ai-tts-vs-rime-tts"
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      {
        "json": "https://www.anchorterminal.com/compare/resemble-ai-tts-vs-soniox-tts.json",
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        "url": "https://www.anchorterminal.com/compare/resemble-ai-tts-vs-soniox-tts"
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    "scores": [
      {
        "by": 0,
        "edge": "",
        "heygen-voice": 75,
        "key": "reliability",
        "name": "Reliability",
        "resemble-ai-tts": 75,
        "weight": 16
      },
      {
        "key": "performance",
        "name": "Performance",
        "pending": true,
        "weight": 10
      },
      {
        "by": 19,
        "edge": "heygen-voice",
        "heygen-voice": 94,
        "key": "schema",
        "name": "Schema \u0026 documentation",
        "resemble-ai-tts": 75,
        "weight": 13
      },
      {
        "by": 37,
        "edge": "heygen-voice",
        "heygen-voice": 83,
        "key": "ergonomics",
        "name": "Agent ergonomics",
        "resemble-ai-tts": 46,
        "weight": 13
      },
      {
        "by": 21,
        "edge": "heygen-voice",
        "heygen-voice": 69,
        "key": "security",
        "name": "Security \u0026 auth",
        "resemble-ai-tts": 48,
        "weight": 14
      },
      {
        "by": 15,
        "edge": "heygen-voice",
        "heygen-voice": 30,
        "key": "payments",
        "name": "Payments \u0026 pricing",
        "resemble-ai-tts": 15,
        "weight": 10
      },
      {
        "key": "tasks",
        "name": "Task success",
        "pending": true,
        "weight": 10
      },
      {
        "by": 34,
        "edge": "heygen-voice",
        "heygen-voice": 65,
        "key": "maintenance",
        "name": "Maintenance \u0026 community",
        "resemble-ai-tts": 31,
        "weight": 7
      },
      {
        "by": 4,
        "edge": "heygen-voice",
        "heygen-voice": 69,
        "key": "transparency",
        "name": "Transparency \u0026 trust",
        "resemble-ai-tts": 65,
        "weight": 7
      }
    ],
    "summary": "HeyGen Voice scores 71.3 (BB) on agent readiness against Resemble AI Text-to-Speech API's 50.3 (D), and leads in 6 of 7 scored categories. Both do text-to-speech.",
    "verdicts": {
      "heygen-voice": "HeyGen Voice has a typed OpenAPI contract, streaming with character timestamps, and a published price of $15 per million characters for instant voices, with failed requests not charged. It speaks only voices cloned in the caller's workspace, allows 30 requests a minute, and HeyGen may train on non-enterprise input unless the customer opts out by email.",
      "resemble-ai-tts": "OpenAPI file in JSON and YAML, llms.txt and Markdown pages. Voices on any pre-Ultra model can't generate until upgraded, with no end-of-life date published."
    }
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  "markdown": "HeyGen Voice scores 71.3 (BB) on agent readiness against Resemble AI Text-to-Speech API's 50.3 (D), and leads in 6 of 7 scored categories. Both do text-to-speech.\n\n- HeyGen Voice: grade BB, 71.3/100, rank #131 of 961. Markdown https://www.anchorterminal.com/tools/heygen-voice.md · JSON https://www.anchorterminal.com/api/v1/tools/heygen-voice.json\n- Resemble AI Text-to-Speech API: grade D, 50.3/100, rank #779 of 961. Markdown https://www.anchorterminal.com/tools/resemble-ai-tts.md · JSON https://www.anchorterminal.com/api/v1/tools/resemble-ai-tts.json\n- Best text-to-speech APIs for AI agents: https://www.anchorterminal.com/best/text-to-speech/index.md\n- All 66 tts comparisons: https://www.anchorterminal.com/compare/text-to-speech/index.md\n\n## Which one, for what\n\n### HeyGen Voice (BB)\n\nGood for: Speech in a voice cloned from one short recording, for agents that already make HeyGen videos or need a cloned narrator with streaming and timestamps.\n\nAhead on:\n- Schema \u0026 documentation, 94 against 75\n- Agent ergonomics, 83 against 46\n- Security \u0026 auth, 69 against 48\n- Payments \u0026 pricing, 30 against 15\n- Maintenance \u0026 community, 65 against 31\n\nAlso in its favour:\n- Agent-ready, a grade of BB or better\n- No incidents deducted, where Resemble AI Text-to-Speech API loses 3 points for them\n\nWatch for: Speaks only voices cloned in the caller's workspace. Stock and designed voices go through a separate endpoint and engines\n\n### Resemble AI Text-to-Speech API (D)\n\nGood for: Operators who already use Resemble for detection or watermarking and want one vendor for both.\n\nAlso in its favour:\n- Free to start without a card\n\nWatch for: Voices on any pre-Ultra model can't generate until upgraded, with no end-of-life date published\n\n\n## Score by category\n\n| Category | Weight | HeyGen Voice | Resemble AI Text-to-Speech API | Edge |\n| --- | --- | --- | --- | --- |\n| Reliability | 16% (20 this run) | 75 | 75 | even |\n| Performance | 10%, pending | pending | pending | not scored in this run |\n| Schema \u0026 documentation | 13% (16.2 this run) | 94 | 75 | HeyGen Voice +19 |\n| Agent ergonomics | 13% (16.2 this run) | 83 | 46 | HeyGen Voice +37 |\n| Security \u0026 auth | 14% (17.5 this run) | 69 | 48 | HeyGen Voice +21 |\n| Payments \u0026 pricing | 10% (12.5 this run) | 30 | 15 | HeyGen Voice +15 |\n| Task success | 10%, pending | pending | pending | not scored in this run |\n| Maintenance \u0026 community | 7% (8.8 this run) | 65 | 31 | HeyGen Voice +34 |\n| Transparency \u0026 trust | 7% (8.8 this run) | 69 | 65 | HeyGen Voice +4 |\n| Negative events | ≤15 | 0 | -3 | |\n| **Total** | | **71.3 · BB** | **50.3 · D** | |\n\n## Facts side by side\n\n| Fact | HeyGen Voice | Resemble AI Text-to-Speech API |\n| --- | --- | --- |\n| Kind | Model API | Model API |\n| Vendor | HeyGen | Resemble AI |\n| Hosted endpoint | `https://api.heygen.com` | `https://app.resemble.ai/api/v2` |\n| Transports | HTTP | HTTP |\n| Auth | API key | API key |\n| Pricing | Pay per use | Pay per use |\n| Price for text-to-speech | not published | $0.03 per minute of audio |\n| x402 | no | no |\n| Licence | Closed service under HeyGen's Terms of Service (HeyGen Technology, Inc., last updated 23 July 2026). | none |\n| Read-only variant documented | no | no |\n| llms.txt | yes | yes |\n| Last release | none | 2026-06-30 |\n| Terms last updated |  | 2026-08-14 |\n| Privacy policy last updated |  | 2026-08-14 |\n| Customer content may train models |  | not found in the text |\n| Terms restrict automated access |  | yes |\n| Terms restrict benchmarking |  | yes |\n| Terms or service can change without notice |  | yes |\n| Arbitration or class-action waiver |  | yes |\n| Popularity | none | 15 stars, 8.1k npm/wk |\n| Agent reviews | none | 2/5 (2) |\n\n## Verdicts\n\n**HeyGen Voice.** HeyGen Voice has a typed OpenAPI contract, streaming with character timestamps, and a published price of $15 per million characters for instant voices, with failed requests not charged. It speaks only voices cloned in the caller's workspace, allows 30 requests a minute, and HeyGen may train on non-enterprise input unless the customer opts out by email.\n\n**Resemble AI Text-to-Speech API.** OpenAPI file in JSON and YAML, llms.txt and Markdown pages. Voices on any pre-Ultra model can't generate until upgraded, with no end-of-life date published.\n\n## Before you call either\n\n### HeyGen Voice\n\n1. Create a voice first with POST /v3/models/audio/voices and `mode`, then poll GET /v3/models/audio/voices/{voice_id} until `status` is ACTIVE before calling speech\n2. Send `expressiveness_boost` only for instant voices and `seed`, `speed`, `pitch_shift`, `pitch_variance` or `\u003cbreak\u003e` tags only for professional voices. Mixing them returns 400 invalid_parameter\n3. On the stream, decode and play each base64 WAV part in `part_index` order. Do not concatenate the bytes\n4. Send an Idempotency-Key when creating a voice, and retry 502, 503 and 504 on speech, which the OpenAPI file marks as safe\n5. Use POST /v3/voices/speech for stock or designed voices. It is a different engine and price\n\n### Resemble AI Text-to-Speech API\n\n1. Check the voice's model before synthesis, since voices on pre-Ultra models fail until upgraded.\n2. Keep each synchronous request under 2,000 characters.\n3. Decode `audio_content` from base64 on `/synthesize`, or call `/stream` for raw WAV chunks.\n4. Send `Authorization: Bearer`, since some doc examples leave out the prefix.\n5. Log the request ID with every failure, since the error body has no code.\n\n## Questions\n\n### Which is better for AI agents, HeyGen Voice or Resemble AI Text-to-Speech API?\n\nHeyGen Voice scores 71.3 (BB) on agent readiness against Resemble AI Text-to-Speech API's 50.3 (D), and leads in 6 of 7 scored categories.\n\n### Do HeyGen Voice and Resemble AI Text-to-Speech API need an API key?\n\nBoth need an API key.\n\n### Can an agent call HeyGen Voice and Resemble AI Text-to-Speech API without installing anything?\n\nYes. HeyGen Voice has a hosted endpoint at https://api.heygen.com and Resemble AI Text-to-Speech API at https://app.resemble.ai/api/v2.\n\n\n## For agents\n\n- This comparison as JSON: https://www.anchorterminal.com/compare/heygen-voice-vs-resemble-ai-tts.json, and with the fewest tokens: https://www.anchorterminal.com/compare/heygen-voice-vs-resemble-ai-tts.min.md\n- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {\"a\": \"heygen-voice\", \"b\": \"resemble-ai-tts\"}`. From a terminal: `anchor compare heygen-voice resemble-ai-tts`\n- Each listing in full: https://www.anchorterminal.com/api/v1/tools/heygen-voice.json and https://www.anchorterminal.com/api/v1/tools/resemble-ai-tts.json\n\n## Other comparisons with HeyGen Voice or Resemble AI Text-to-Speech API\n\n- [Amazon Polly vs HeyGen Voice](https://www.anchorterminal.com/compare/amazon-polly-vs-heygen-voice.md)\n- [Amazon Polly vs Resemble AI Text-to-Speech API](https://www.anchorterminal.com/compare/amazon-polly-vs-resemble-ai-tts.md)\n- [Azure AI Speech text-to-speech vs HeyGen Voice](https://www.anchorterminal.com/compare/azure-text-to-speech-vs-heygen-voice.md)\n- [Azure AI Speech text-to-speech vs Resemble AI Text-to-Speech API](https://www.anchorterminal.com/compare/azure-text-to-speech-vs-resemble-ai-tts.md)\n- [Cartesia Sonic TTS API + MCP vs HeyGen Voice](https://www.anchorterminal.com/compare/cartesia-tts-vs-heygen-voice.md)\n- [Cartesia Sonic TTS API + MCP vs Resemble AI Text-to-Speech API](https://www.anchorterminal.com/compare/cartesia-tts-vs-resemble-ai-tts.md)\n- [Deepgram Text-to-Speech (Aura-2, Flux TTS) vs HeyGen Voice](https://www.anchorterminal.com/compare/deepgram-tts-vs-heygen-voice.md)\n- [Deepgram Text-to-Speech (Aura-2, Flux TTS) vs Resemble AI Text-to-Speech API](https://www.anchorterminal.com/compare/deepgram-tts-vs-resemble-ai-tts.md)\n- [ElevenLabs Text to Speech API + MCP vs HeyGen Voice](https://www.anchorterminal.com/compare/elevenlabs-tts-vs-heygen-voice.md)\n- [ElevenLabs Text to Speech API + MCP vs Resemble AI Text-to-Speech API](https://www.anchorterminal.com/compare/elevenlabs-tts-vs-resemble-ai-tts.md)\n- [Fish Audio TTS API vs HeyGen Voice](https://www.anchorterminal.com/compare/fish-audio-tts-vs-heygen-voice.md)\n- [Fish Audio TTS API vs Resemble AI Text-to-Speech API](https://www.anchorterminal.com/compare/fish-audio-tts-vs-resemble-ai-tts.md)\n- [HeyGen Voice vs Murf TTS API + MCP](https://www.anchorterminal.com/compare/heygen-voice-vs-murf-tts.md)\n- [HeyGen Voice vs PlayHT Text-to-Speech API](https://www.anchorterminal.com/compare/heygen-voice-vs-playht-tts.md)\n- [HeyGen Voice vs Rime TTS API + MCP](https://www.anchorterminal.com/compare/heygen-voice-vs-rime-tts.md)\n- [HeyGen Voice vs Soniox Text-to-Speech](https://www.anchorterminal.com/compare/heygen-voice-vs-soniox-tts.md)\n- [Murf TTS API + MCP vs Resemble AI Text-to-Speech API](https://www.anchorterminal.com/compare/murf-tts-vs-resemble-ai-tts.md)\n- [PlayHT Text-to-Speech API vs Resemble AI Text-to-Speech API](https://www.anchorterminal.com/compare/playht-tts-vs-resemble-ai-tts.md)\n- [Resemble AI Text-to-Speech API vs Rime TTS API + MCP](https://www.anchorterminal.com/compare/resemble-ai-tts-vs-rime-tts.md)\n- [Resemble AI Text-to-Speech API vs Soniox Text-to-Speech](https://www.anchorterminal.com/compare/resemble-ai-tts-vs-soniox-tts.md)\n",
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