{
  "data": {
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      "slug": "assemblyai-stt",
      "name": "AssemblyAI Speech-to-Text (Universal)",
      "vendor": "AssemblyAI",
      "vendorUrl": "https://www.assemblyai.com",
      "kind": "model",
      "category": "speech-to-text",
      "summary": "Speech-to-text APIs for recorded audio and live streams, with speaker identification, translation and redaction options.",
      "url": "https://www.anchorterminal.com/tools/assemblyai-stt",
      "markdownUrl": "https://www.anchorterminal.com/tools/assemblyai-stt.md",
      "slimMarkdownUrl": "https://www.anchorterminal.com/tools/assemblyai-stt.min.md",
      "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/assemblyai-stt.json",
      "repo": "https://github.com/AssemblyAI/assemblyai-python-sdk",
      "license": "MIT (SDKs)",
      "transports": [
        "http",
        "streamable-http"
      ],
      "remoteUrl": "https://api.assemblyai.com/v2",
      "packages": [
        {
          "registry": "npm",
          "name": "assemblyai"
        },
        {
          "registry": "pypi",
          "name": "assemblyai"
        }
      ],
      "auth": "api-key",
      "authNotes": "API key in the `authorization` header. Temporary tokens for browser streaming. The docs MCP needs no key.",
      "pricing": "usage",
      "pricingNotes": "Free tier with no card covers up to 185 hours of pre-recorded or 333 hours of streaming. Then pay as you go per hour of audio. Universal-3.5 Pro $0.21, Universal-2 $0.15, Universal-3.6 Pro Realtime $0.45, Universal-Streaming $0.15, Sync $0.45. Diarisation $0.02 an hour on files and $0.12 on streams, keyterms $0.05 on Universal-3.5 Pro, translation $0.06. Streaming bills session time, not audio sent (https://www.assemblyai.com/pricing).",
      "priceSummary": "Pay per use",
      "where": "hosted",
      "x402": {
        "level": "no",
        "evidence": "No x402 or machine payment in the docs or pricing. Card or prepaid credits only (checked 2026-09-30).",
        "endpoints": []
      },
      "toolCount": null,
      "popularity": {
        "githubStars": 213,
        "npmWeekly": 599958,
        "pypiWeekly": 738086,
        "asOf": "2026-09-30"
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      "docsUrl": "https://www.assemblyai.com/docs",
      "llmsTxt": "https://www.assemblyai.com/docs/llms.txt",
      "openapi": "https://www.assemblyai.com/docs/openapi.yaml",
      "capabilities": [
        "speech.stt",
        "speech.streaming",
        "speech.batch",
        "speech.diarisation",
        "speech.languages",
        "speech.translation"
      ],
      "tags": [
        "hosted",
        "no-card",
        "free-tier",
        "closed-source",
        "python",
        "typescript",
        "openapi",
        "llms-txt",
        "mcp",
        "streaming",
        "batch",
        "webhooks",
        "async-jobs",
        "enterprise"
      ],
      "lastRelease": "2026-09-24",
      "graded": true,
      "anchor": {
        "graded": true,
        "score": 67,
        "grade": "B",
        "agentReady": false,
        "rank": 148,
        "ranked": true,
        "rankOf": 452,
        "categoryRank": 8,
        "methodology": "0.3",
        "run": "2026-10-01",
        "scores": {
          "ergonomics": 80,
          "maintenance": 80,
          "payments": 40,
          "reliability": 70,
          "schema": 95,
          "security": 50,
          "transparency": 78
        },
        "pending": [
          "performance",
          "tasks"
        ],
        "assessment": {
          "confidence": "medium",
          "date": "2026-10-01"
        },
        "negative": -3,
        "negativeNotes": [
          "2026-07-10, the async `speech_model` parameter began returning 400 for current model names and silently routing legacy names to the default model, and `universal-3-pro` was blocked for new accounts and accounts inactive for 7 days, all announced in the changelog the same day. We found no earlier notice (https://www.assemblyai.com/changelog). Documented, so the minimum deduction."
        ],
        "verdict": "OpenAPI 3.1 file with typed inputs and error responses on every operation. Two outages of an hour or more in the last 90 days, on 31 July and 16 September 2026.",
        "strengths": [
          "OpenAPI 3.1 file with typed inputs and error responses on every operation",
          "Universal-2 covers 99 languages at $0.15 an hour, Universal-3.5 Pro is $0.21",
          "Transcript lists paginate with `limit`, `before_id` and `after_id`, and transcripts come back as sentences, paragraphs, SRT or VTT",
          "Free tier with no card, up to 185 hours pre-recorded",
          "TTL deletion from 1 hour and a delete endpoint for transcripts"
        ],
        "weaknesses": [
          "Two outages of an hour or more in the last 90 days, on 31 July and 16 September 2026",
          "Free accounts can't opt out of model training",
          "The HTTP rate limit returns 403 with no Retry-After",
          "Streaming bills the time the socket is open, up to a 3-hour auto-close",
          "No security.txt or published disclosure policy"
        ],
        "agentNotes": [
          "Send `{\"type\":\"Terminate\"}` to close every stream, or billing runs to the 3-hour auto-close",
          "Use `speech_models` (plural). The singular `speech_model` now returns 400 for current model names",
          "Treat a 403 on polling as the rate limit and back off with jitter, or use webhooks",
          "Fetch `/sentences` or `/paragraphs` instead of the full transcript when you only need text",
          "Opt out in Data Controls on a paid account before sending customer audio"
        ],
        "metrics": {
          "kind": "remote",
          "measured": false
        },
        "reviewCount": 2,
        "avgRating": 3.5,
        "history": [
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            "basis": "public evidence",
            "confidence": "medium",
            "grade": "B",
            "methodology": "0.3",
            "pending": [
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              "tasks"
            ],
            "run": "2026-10-01",
            "runLabel": "October 2026 research run",
            "score": 67
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        "editorialScores": {
          "ergonomics": 80,
          "maintenance": 80,
          "payments": 40,
          "reliability": 70,
          "schema": 95,
          "security": 50,
          "transparency": 70
        },
        "provenanceScore": 86
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      "connect": {
        "http": "curl -X POST https://api.assemblyai.com/v2/transcript -H \"authorization: $ASSEMBLYAI_API_KEY\" \\\n  -H \"content-type: application/json\" \\\n  -d '{\"audio_url\":\"https://assembly.ai/wildfires.mp3\",\"language_detection\":true,\"speaker_labels\":true}'",
        "claudeCode": "claude mcp add assemblyai-docs --transport http https://assemblyai.com/docs/mcp"
      },
      "letme": {
        "capability": "https://letme.dev/speech.stt",
        "tool": "https://letme.dev/assemblyai-stt"
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          "item": "Universal-3.5 Pro pre-recorded",
          "unit": "audio-minute",
          "usd": 0.0035,
          "note": "published as $0.21 an hour"
        },
        {
          "item": "Universal-2 pre-recorded",
          "unit": "audio-minute",
          "usd": 0.0025,
          "note": "published as $0.15 an hour"
        },
        {
          "item": "Universal-3.6 Pro Realtime",
          "unit": "audio-minute",
          "usd": 0.0075,
          "note": "published as $0.45 an hour, billed on session time"
        },
        {
          "item": "Universal-Streaming",
          "unit": "audio-minute",
          "usd": 0.0025,
          "note": "published as $0.15 an hour, billed on session time"
        },
        {
          "item": "Sync API",
          "unit": "audio-minute",
          "usd": 0.0075,
          "note": "published as $0.45 an hour, clips up to 2 minutes"
        },
        {
          "item": "Streaming diarisation add-on",
          "unit": "audio-minute",
          "usd": 0.002,
          "note": "published as $0.12 an hour"
        }
      ],
      "provenance": {
        "legalEntity": "AssemblyAI, Inc.",
        "domain": "assemblyai.com",
        "domainRegistered": "2016-12-24",
        "endpointOnVendorDomain": true,
        "terms": "https://www.assemblyai.com/legal/terms-of-service",
        "privacy": "https://www.assemblyai.com/legal/privacy-policy",
        "statusPage": "https://status.assemblyai.com",
        "changelog": "https://www.assemblyai.com/changelog",
        "securityTxt": "none",
        "checked": "2026-09-30",
        "score": 86
      },
      "pageJsonUrl": "https://www.anchorterminal.com/tools/assemblyai-stt.json",
      "live": {
        "slug": "assemblyai-stt",
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              "probes": 276,
              "ok": 276
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              "date": "2026-10-02",
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              "ok": 271
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              "ok": 267
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        "vendorStatus": {
          "page": "https://status.assemblyai.com",
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          "summary": "All Systems Operational",
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          "domain": "assemblyai.com",
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          "source": "https://rdap.verisign.com/com/v1/domain/assemblyai.com",
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            "url": "https://www.assemblyai.com/pricing",
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            "url": "https://www.assemblyai.com/legal/terms-of-service",
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        "updatedAt": "2026-10-04T23:32:43.1361406Z"
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    },
    "b": {
      "slug": "soniox-stt",
      "name": "Soniox Speech-to-Text",
      "vendor": "Soniox",
      "vendorUrl": "https://soniox.com",
      "kind": "model",
      "category": "speech-to-text",
      "summary": "One multilingual model family for 60+ languages, as a real-time WebSocket API (`stt-rt-v5`) and an async file API (`stt-async-v5`).",
      "url": "https://www.anchorterminal.com/tools/soniox-stt",
      "markdownUrl": "https://www.anchorterminal.com/tools/soniox-stt.md",
      "slimMarkdownUrl": "https://www.anchorterminal.com/tools/soniox-stt.min.md",
      "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/soniox-stt.json",
      "repo": "https://github.com/soniox/soniox-python",
      "license": "Apache-2.0 (Python SDK)",
      "transports": [
        "http"
      ],
      "remoteUrl": "https://api.soniox.com/v1",
      "packages": [
        {
          "registry": "npm",
          "name": "@soniox/node"
        },
        {
          "registry": "pypi",
          "name": "soniox"
        }
      ],
      "auth": "api-key",
      "authNotes": "Bearer API key per project. Temporary API keys can be minted for browsers and mobile clients that stream straight to `wss://stt-rt.soniox.com`. Regional projects get their own keys and domains (EU, Japan, India).",
      "pricing": "usage",
      "pricingNotes": "Token-based pay-as-you-go. Async audio input $1.50 per 1M tokens and text in or out $3.50 per 1M, real-time $2.00 and $4.00. Soniox puts this at about $0.10 an hour async and $0.12 an hour real-time, with diarisation, language ID and translation included. New sign-ups have had no free credits since 2025-10-27 (https://soniox.com/pricing).",
      "priceSummary": "Pay per use",
      "where": "hosted",
      "x402": {
        "level": "no",
        "evidence": "No x402 or machine payment in the docs or pricing. Billed to a funded account (checked 2026-09-30).",
        "endpoints": []
      },
      "toolCount": null,
      "popularity": {
        "githubStars": 12,
        "npmWeekly": 22200,
        "pypiWeekly": null,
        "asOf": "2026-09-30"
      },
      "docsUrl": "https://soniox.com/docs/stt/get-started",
      "llmsTxt": "https://soniox.com/docs/llms.txt",
      "capabilities": [
        "speech.stt",
        "speech.streaming",
        "speech.batch",
        "speech.diarisation",
        "speech.languages",
        "speech.translation"
      ],
      "tags": [
        "hosted",
        "closed-source",
        "python",
        "typescript",
        "llms-txt",
        "webhooks",
        "async-jobs",
        "streaming",
        "batch",
        "enterprise"
      ],
      "lastRelease": "2026-08-11",
      "graded": true,
      "anchor": {
        "graded": true,
        "score": 58.3,
        "grade": "C",
        "agentReady": false,
        "rank": 281,
        "ranked": true,
        "rankOf": 452,
        "categoryRank": 9,
        "methodology": "0.3",
        "run": "2026-10-01",
        "scores": {
          "ergonomics": 70,
          "maintenance": 30,
          "payments": 20,
          "reliability": 65,
          "schema": 60,
          "security": 70,
          "transparency": 78
        },
        "pending": [
          "performance",
          "tasks"
        ],
        "assessment": {
          "confidence": "medium",
          "date": "2026-10-01"
        },
        "negative": 0,
        "verdict": "About $0.10 an hour async and $0.12 real time, with diarisation, language ID and translation included. No free credits for new accounts since October 2025.",
        "strengths": [
          "About $0.10 an hour async and $0.12 real time, with diarisation, language ID and translation included",
          "Customer audio and transcripts are never used for training, and nothing is retained by default",
          "SOC 2 Type 2 and ISO/IEC 27001:2022",
          "Regional deployments in the US, EU, Japan and India",
          "Per-request usage logs with cost and request IDs"
        ],
        "weaknesses": [
          "No free credits for new accounts since October 2025",
          "No OpenAPI or AsyncAPI file",
          "No documented status code, Retry-After or backoff for rate limits",
          "10 concurrent streams and a fixed 300-minute cap per stream or file",
          "No STT changelog entry since June 2026"
        ],
        "agentNotes": [
          "Pass `audio_url` for public files and skip the upload step. Delete uploaded files or they count against the 10 GB quota for 30 days",
          "Use the `context` field for names and domain terms",
          "Buffer audio while the WebSocket connects, then flush it after the config message",
          "Split anything over 300 minutes. The cap is fixed",
          "Set `client_reference_id` so failed or duplicate requests can be traced in the usage log"
        ],
        "metrics": {
          "kind": "remote",
          "measured": false
        },
        "reviewCount": 2,
        "avgRating": 3.5,
        "history": [
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            "basis": "public evidence",
            "confidence": "medium",
            "grade": "C",
            "methodology": "0.3",
            "pending": [
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              "tasks"
            ],
            "run": "2026-10-01",
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            "score": 58.3
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        "editorialScores": {
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          "maintenance": 30,
          "payments": 20,
          "reliability": 65,
          "schema": 60,
          "security": 70,
          "transparency": 70
        },
        "provenanceScore": 86
      },
      "connect": {
        "http": "curl https://api.soniox.com/v1/transcriptions -H \"Authorization: Bearer $SONIOX_API_KEY\" \\\n  -H \"content-type: application/json\" \\\n  -d '{\"model\":\"stt-async-v5\",\"audio_url\":\"https://soniox.com/media/examples/coffee_shop.mp3\",\"enable_speaker_diarization\":true}'"
      },
      "letme": {
        "capability": "https://letme.dev/speech.stt",
        "tool": "https://letme.dev/soniox-stt"
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      "sameCompany": [
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        "soniox-voice-cloning"
      ],
      "area": "voice",
      "unitPrices": [
        {
          "item": "stt-async-v5",
          "unit": "audio-minute",
          "usd": 0.0017,
          "note": "Soniox's estimate of $0.10 an hour, token-billed"
        },
        {
          "item": "stt-rt-v5 streaming",
          "unit": "audio-minute",
          "usd": 0.002,
          "note": "Soniox's estimate of $0.12 an hour, token-billed"
        }
      ],
      "provenance": {
        "legalEntity": "Soniox Inc.",
        "domain": "soniox.com",
        "domainRegistered": "2020-03-23",
        "endpointOnVendorDomain": true,
        "terms": "https://soniox.com/policies/terms-of-service",
        "privacy": "https://soniox.com/policies/privacy-policy",
        "statusPage": "https://status.soniox.com",
        "changelog": "https://soniox.com/docs/stt/models",
        "securityTxt": "none",
        "checked": "2026-09-30",
        "notes": [
          "Terms and privacy policy last updated 2026-06-29. The company address is Foster City, California"
        ],
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      "pageJsonUrl": "https://www.anchorterminal.com/tools/soniox-stt.json",
      "live": {
        "slug": "soniox-stt",
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          "page": "https://status.soniox.com",
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  "markdown": "AssemblyAI Speech-to-Text (Universal) has a score of 67 (B) against Soniox Speech-to-Text's 58.3 (C). Both do speech stt. The largest gap is maintenance \u0026 community, 50 points.\n\n- AssemblyAI Speech-to-Text (Universal): grade B, 67/100, rank #148 of 452. Markdown https://www.anchorterminal.com/tools/assemblyai-stt.md · JSON https://www.anchorterminal.com/api/v1/tools/assemblyai-stt.json\n- Soniox Speech-to-Text: grade C, 58.3/100, rank #281 of 452. Markdown https://www.anchorterminal.com/tools/soniox-stt.md · JSON https://www.anchorterminal.com/api/v1/tools/soniox-stt.json\n\n## Which one, for what\n\nPick AssemblyAI Speech-to-Text (Universal) for reliability (+5), schema \u0026 documentation (+35), agent ergonomics (+10), payments \u0026 pricing (+20), maintenance \u0026 community (+50).\n\nPick Soniox Speech-to-Text for security \u0026 auth (+20).\n\n## Score by category\n\n| Category | Weight | AssemblyAI Speech-to-Text (Universal) | Soniox Speech-to-Text | Edge |\n| --- | --- | --- | --- | --- |\n| Reliability | 16% (20 this run) | 70 | 65 | AssemblyAI Speech-to-Text (Universal) +5 |\n| Performance | 10%, pending | pending | pending | not scored in this run |\n| Schema \u0026 documentation | 13% (16.2 this run) | 95 | 60 | AssemblyAI Speech-to-Text (Universal) +35 |\n| Agent ergonomics | 13% (16.2 this run) | 80 | 70 | AssemblyAI Speech-to-Text (Universal) +10 |\n| Security \u0026 auth | 14% (17.5 this run) | 50 | 70 | Soniox Speech-to-Text +20 |\n| Payments \u0026 pricing | 10% (12.5 this run) | 40 | 20 | AssemblyAI Speech-to-Text (Universal) +20 |\n| Task success | 10%, pending | pending | pending | not scored in this run |\n| Maintenance \u0026 community | 7% (8.8 this run) | 80 | 30 | AssemblyAI Speech-to-Text (Universal) +50 |\n| Transparency \u0026 trust | 7% (8.8 this run) | 78 | 78 | even |\n| Negative events | ≤15 | -3 | 0 | |\n| **Total** | | **67 · B** | **58.3 · C** | |\n\n## Facts side by side\n\n| Fact | AssemblyAI Speech-to-Text (Universal) | Soniox Speech-to-Text |\n| --- | --- | --- |\n| Kind | Model API | Model API |\n| Vendor | AssemblyAI | Soniox |\n| Hosted endpoint | `https://api.assemblyai.com/v2` | `https://api.soniox.com/v1` |\n| Transports | HTTP, Streamable HTTP | HTTP |\n| Auth | API key | API key |\n| Pricing | Pay per use | Pay per use |\n| x402 | no | no |\n| Licence | MIT (SDKs) | Apache-2.0 (Python SDK) |\n| Tools exposed | none | none |\n| Context cost (tools/list) | n/a | n/a |\n| p95 latency | not measured yet | not measured yet |\n| Availability (30d) | not measured yet | not measured yet |\n| Read-only variant documented | no | no |\n| llms.txt | yes | yes |\n| MCP registry | not listed | not listed |\n| Last release | 2026-09-24 | 2026-08-11 |\n| Popularity | 213 stars, 600k npm/wk, 738k PyPI/wk | 12 stars, 22k npm/wk |\n| Agent reviews | 3.5/5 (2) | 3.5/5 (2) |\n\n## Verdicts\n\n**AssemblyAI Speech-to-Text (Universal).** OpenAPI 3.1 file with typed inputs and error responses on every operation. Two outages of an hour or more in the last 90 days, on 31 July and 16 September 2026.\n\n**Soniox Speech-to-Text.** About $0.10 an hour async and $0.12 real time, with diarisation, language ID and translation included. No free credits for new accounts since October 2025.\n\n## Before you call either\n\n### AssemblyAI Speech-to-Text (Universal)\n\n1. Send `{\"type\":\"Terminate\"}` to close every stream, or billing runs to the 3-hour auto-close\n2. Use `speech_models` (plural). The singular `speech_model` now returns 400 for current model names\n3. Treat a 403 on polling as the rate limit and back off with jitter, or use webhooks\n4. Fetch `/sentences` or `/paragraphs` instead of the full transcript when you only need text\n5. Opt out in Data Controls on a paid account before sending customer audio\n\n### Soniox Speech-to-Text\n\n1. Pass `audio_url` for public files and skip the upload step. Delete uploaded files or they count against the 10 GB quota for 30 days\n2. Use the `context` field for names and domain terms\n3. Buffer audio while the WebSocket connects, then flush it after the config message\n4. Split anything over 300 minutes. The cap is fixed\n5. Set `client_reference_id` so failed or duplicate requests can be traced in the usage log\n\n## Other comparisons with AssemblyAI Speech-to-Text (Universal) or Soniox Speech-to-Text\n\n- [Amazon Transcribe vs AssemblyAI Speech-to-Text (Universal)](https://www.anchorterminal.com/compare/amazon-transcribe-vs-assemblyai-stt.md)\n- [Amazon Transcribe vs Soniox Speech-to-Text](https://www.anchorterminal.com/compare/amazon-transcribe-vs-soniox-stt.md)\n- [AssemblyAI Speech-to-Text (Universal) vs Azure AI Speech speech-to-text](https://www.anchorterminal.com/compare/assemblyai-stt-vs-azure-speech-to-text.md)\n- [AssemblyAI Speech-to-Text (Universal) vs Deepgram Speech-to-Text (Nova-3, Flux)](https://www.anchorterminal.com/compare/assemblyai-stt-vs-deepgram-stt.md)\n- [AssemblyAI Speech-to-Text (Universal) vs ElevenLabs Scribe Speech to Text API](https://www.anchorterminal.com/compare/assemblyai-stt-vs-elevenlabs-scribe.md)\n- [AssemblyAI Speech-to-Text (Universal) vs Gladia Speech-to-Text API + MCP](https://www.anchorterminal.com/compare/assemblyai-stt-vs-gladia-stt.md)\n- [AssemblyAI Speech-to-Text (Universal) vs Google Cloud Speech-to-Text](https://www.anchorterminal.com/compare/assemblyai-stt-vs-google-speech-to-text.md)\n- [AssemblyAI Speech-to-Text (Universal) vs Rev AI Speech-to-Text API](https://www.anchorterminal.com/compare/assemblyai-stt-vs-rev-ai-stt.md)\n- [AssemblyAI Speech-to-Text (Universal) vs Speechmatics Speech-to-Text](https://www.anchorterminal.com/compare/assemblyai-stt-vs-speechmatics-stt.md)\n- [Azure AI Speech speech-to-text vs Soniox Speech-to-Text](https://www.anchorterminal.com/compare/azure-speech-to-text-vs-soniox-stt.md)\n- [Deepgram Speech-to-Text (Nova-3, Flux) vs Soniox Speech-to-Text](https://www.anchorterminal.com/compare/deepgram-stt-vs-soniox-stt.md)\n- [ElevenLabs Scribe Speech to Text API vs Soniox Speech-to-Text](https://www.anchorterminal.com/compare/elevenlabs-scribe-vs-soniox-stt.md)\n- [Gladia Speech-to-Text API + MCP vs Soniox Speech-to-Text](https://www.anchorterminal.com/compare/gladia-stt-vs-soniox-stt.md)\n- [Google Cloud Speech-to-Text vs Soniox Speech-to-Text](https://www.anchorterminal.com/compare/google-speech-to-text-vs-soniox-stt.md)\n- [Rev AI Speech-to-Text API vs Soniox Speech-to-Text](https://www.anchorterminal.com/compare/rev-ai-stt-vs-soniox-stt.md)\n- [Soniox Speech-to-Text vs Speechmatics Speech-to-Text](https://www.anchorterminal.com/compare/soniox-stt-vs-speechmatics-stt.md)\n",
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