# PlayHT Text-to-Speech API vs Smallest.ai Lightning TTS

> Smallest.ai Lightning TTS scores 64.4 (B) to PlayHT Text-to-Speech's 4.1 (F) for text-to-speech. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/playht-tts-vs-smallest-lightning-tts
- Markdown: https://www.anchorterminal.com/compare/playht-tts-vs-smallest-lightning-tts.md (~4,800 tokens)
- Site index for agents: https://www.anchorterminal.com/llms.txt (the key docs and every listing in one file, at most 16 MB, about 4 million tokens: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- MCP: https://www.anchorterminal.com/mcp (the whole catalogue as tools, no key)
- DNS: dig +short TXT <slug>.grade.anchorterminal.com (the grade as a DNS TXT record, for a sandbox with no HTTP where names still resolve; also top., best.<category>. and <a>.vs.<b>. under the zone, and the same under grade.letme.dev)
- Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data)
- Updated: 2026-11-07

PlayHT Text-to-Speech API shut down on 2025-12-31. Smallest.ai Lightning TTS scores 64.4 (B) on agent readiness against PlayHT Text-to-Speech API's 4.1 (F), and leads in every scored category. Both do text-to-speech.

- PlayHT Text-to-Speech API: grade F, 4.1/100, rank retired, not ranked. Markdown https://www.anchorterminal.com/tools/playht-tts.md · JSON https://www.anchorterminal.com/api/v1/tools/playht-tts.json
- Smallest.ai Lightning TTS: grade B, 64.4/100, rank #471 of 1510. Markdown https://www.anchorterminal.com/tools/smallest-lightning-tts.md · JSON https://www.anchorterminal.com/api/v1/tools/smallest-lightning-tts.json
- Best text-to-speech APIs for AI agents: https://www.anchorterminal.com/best/text-to-speech/index.md
- All 148 tts comparisons: https://www.anchorterminal.com/compare/text-to-speech/index.md

## Which one, for what

### PlayHT Text-to-Speech API (F)

Good for: Nothing new. It shut down on 2025-12-31.

Also in its favour:
- A hosted endpoint, with nothing to install

Watch for: api.play.ht doesn't resolve, so every call fails

### Smallest.ai Lightning TTS (B)

Good for: Low-latency speech for voice agents, with English, Hindi code-switching and Indic voices.

Ahead on:
- Reliability, 58 against 0
- Schema & documentation, 92 against 31
- Agent ergonomics, 72 against 0
- Security & auth, 52 against 0
- Payments & pricing, 40 against 0
- Maintenance & community, 68 against 0
- Transparency & trust, 70 against 35

Also in its favour:
- Still running. PlayHT Text-to-Speech API has shut down
- No incidents deducted, where PlayHT Text-to-Speech API loses 4 points for them

Watch for: `lightning_v3.1`, the default model, retires on 30 November 2026 after a 2 November notice, and clones made on it stop working


## Why the edge

### Agent ergonomics: Smallest.ai Lightning TTS +72

- PlayHT Text-to-Speech API (0): No live surface to call, so every line scores 0.
- Smallest.ai Lightning TTS (72): API reading of the checklist. Eight output formats, a choice of sample rate and word timestamps only when asked (22 of 25). Voices are listed per model and the docs say they filter by language and accent. Paging wasn't confirmed (14 of 20). Errors carry `error` and `message` fields with a shared status-code guide, without TTS-specific codes (14 of 20). Synthesis is stateless and `request_id` is echoed for correlation, but there is no idempotency key and billing of a retried request isn't stated (10 of 20). Two required fields, `text` and `voice_id`, but the default model retires on 30 November. Official Python and Node SDKs, with the Node SDK last published in May 2025 (12 of 15). Total 72.

### Maintenance & community: Smallest.ai Lightning TTS +68

- PlayHT Text-to-Speech API (0): No release or changelog entry in the last 90 days or the last year (0). No support channel (0). SDKs abandoned (0). No package health to judge (0).
- Smallest.ai Lightning TTS (68): Read as a model. The newest Lightning changelog entry is dated 2 November 2026 (the v3.1 retirement notice), after a preview checkpoint on 29 October (30). Dated Lightning entries on 10, 23 and 28 August, 29 September, 14, 17 and 29 October and 2 November count, less 5 for churn, because the default model retires 28 days after its notice and clones made on it stop working (15 of 20). Public changelog, email support and a Discord server, with no evidence read of how they answer (10 of 15). The Python SDK `smallestai` 5.14.0 dates from 7 October, but the npm Node SDK has not been published since May 2025 (8 of 15). The Python SDK repository runs CI and release workflows, but has no licence file (5 of 10). Total 68.

### Schema & documentation: Smallest.ai Lightning TTS +61

- PlayHT Text-to-Speech API (31): What's left is the docs, still served at docs.play.ht with pages last updated on 9 September 2025 and no shutdown notice. The Markdown copy of each reference page embeds an OpenAPI 3.0.3 fragment for its one operation, with typed enums and seven response codes on the streaming endpoint, and an llms.txt indexes the guides and reference pages as Markdown. Both point at https://api.play.ht, which no longer resolves, and describe the API as live. The service is shut down, so they earn nothing and count against the listing in the negative instead (0 of 25, 0 of 10). The getting-started and streaming pages state purpose and limits (8 of 20). Typed request fields with engine names and a 20,000-character streaming cap (10 of 15). Response codes and examples on the reference pages (8 of 15). Versioned `/api/v2` path, and docs.play.ht/changelog returns 404 (5 of 15). Total 31. A model reading these pages or the llms.txt would call an API that doesn't exist.
- Smallest.ai Lightning TTS (92): OpenAPI 3.1 for the sync and SSE routes and AsyncAPI 2.6 for the WebSocket, with request and event schemas (25). llms.txt and a Markdown copy of every page (10). A transport guide, model cards and the compare page say which model and transport suit which job, but changelog entries correct the language lists and enums the docs and spec carried (15 of 20). Typed fields with enums for model, sample rate, language and output format, an 8,000-character limit and pattern rules on `session_id` and `request_id` (14 of 15). Examples in curl, Python and JavaScript, with error bodies on the reference and a shared error page (13 of 15). Versioned `/v1` paths, a dated Lightning changelog and dated preview checkpoints (15). Total 92.

### Reliability: Smallest.ai Lightning TTS +58

- PlayHT Text-to-Speech API (0): Retired. On 2026-10-17 api.play.ht and play.ht didn't resolve, so nothing answers a call. Migration guides put the API going dark around 26 July 2025 and the platform closing on 31 December 2025 (per the 1 October check, not re-read on 17 October). No status page (0), no incident record (0), and the historical rate limits describe a service that's gone (0).
- Smallest.ai Lightning TTS (58): BetterStack status page at status.smallest.ai with components for the Global, India and USA APIs (one health check covers the Agents and Models APIs), docs, the app and Electron, and per-component history (20). In the 90 days from 8 August the health checks on the shared API failed in all three regions on 9, 10, 13, 14 and 15 September (about 8, 21, 33, 17 and 64 minutes of flapping), in the Global and India regions on 11 and 17 September (12 minutes each), and in the USA region alone on 1, 3, 5, 12, 21 and 30 September (6 to 62 minutes) and 6 October (12 minutes). Outages in every region at once are read as wide errors, so several majors (0). Limits are published with numbers but disagree. The limits page says one TTS request at a time per account with up to five sockets, the Lightning v3.1 Pro card says 10 concurrent and the pricing page says 15 streams and 100 requests a minute on pay as you go (8 of 15). 429 is documented with exponential backoff from 500 ms to 30 s and Retry-After when present, and the limits page tells clients to expect 429s at the concurrency ceiling (15). An infrastructure SLA of 99.99 per cent is named for Enterprise only, with no terms, and the terms disclaim any availability commitment (5 of 10). `lightning_v3.1_pro` is stable and only the dated checkpoint is preview (10). 20 + 0 + 8 + 15 + 5 + 10 = 58.

### Security & auth: Smallest.ai Lightning TTS +52

- PlayHT Text-to-Speech API (0): No live surface. Historically a secret key plus a user ID in two headers, with no scopes. Accounts, audio and clones were reportedly deleted at shutdown with no export. Nothing left to score (0).
- Smallest.ai Lightning TTS (52): Model reading of the checklist, with training and retention in place of the least-privilege and injection lines. Plain `sk_` keys per organisation, shown once, revoked at once and deletable, with one key per environment advised. The docs say a key grants full account access, and no scope is offered. Short-lived access tokens (`wat_`, 30 to 900 seconds) cover only inference routes and can't mint tokens (22 of 30). The error reference documents the key as a `?token=` query parameter for browser WebSockets, and the token guide passes access tokens as `?api_key=` on the STT socket, so 10 off (12 of 30). The terms (21 October 2026) say Smallest won't use user content or input to train or improve its services. The privacy policy (18 September 2026) lists improving the services with machine learning as a use of usage data and doesn't address uploaded audio or text either way (15 of 20). Zero data retention and the `x-expire-content` header are Enterprise only, or a $1,000 a month HIPAA add-on on pay as you go. Other plans keep content readable in logs and the dashboard, with no retention period published (5 of 15). Usage is tracked per key, request rows sit in a dashboard log viewer, and every response carries `x-request-id`. No audit log of key actions was found (10 of 15). security.txt is valid to 31 December 2026 and the site footer claims SOC 2, GDPR and HIPAA compliance, while the pricing page lists SOC 2 compliance only on Enterprise. No bug bounty, disclosure policy or public advisories found (10 of 20). Total 52.

### Payments & pricing: Smallest.ai Lightning TTS +40

- PlayHT Text-to-Speech API (0): Nothing can be bought. No x402 was ever documented (0), no live pricing (0), no free tier (0), no signup (0).
- Smallest.ai Lightning TTS (40): No x402, MPP or L402 (0). Per-character prices for both models published without a login (20). Pay as you go starts with $10 of trial credits, which the terms also describe, and no page says a card is needed to claim them, read as inworld-tts's free plan was (20). A person signs up in a browser at app.smallest.ai and creates the key in the dashboard, and top-ups go to a card on file (0). Total 40.

## Score by category

| Category | Weight | PlayHT Text-to-Speech API | Smallest.ai Lightning TTS | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 0 | 58 | Smallest.ai Lightning TTS +58 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 31 | 92 | Smallest.ai Lightning TTS +61 |
| Agent ergonomics | 13% (16.2 this run) | 0 | 72 | Smallest.ai Lightning TTS +72 |
| Security & auth | 14% (17.5 this run) | 0 | 52 | Smallest.ai Lightning TTS +52 |
| Payments & pricing | 10% (12.5 this run) | 0 | 40 | Smallest.ai Lightning TTS +40 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 0 | 68 | Smallest.ai Lightning TTS +68 |
| Transparency & trust | 7% (8.8 this run) | 35 | 70 | Smallest.ai Lightning TTS +35 |
| Negative events | ≤15 | -4 | 0 | |
| **Total** | | **4.1 · F** | **64.4 · B** | |

## Facts side by side

| Fact | PlayHT Text-to-Speech API | Smallest.ai Lightning TTS |
| --- | --- | --- |
| Kind | Model API | Model API |
| Vendor | PlayHT | Smallest AI |
| Hosted endpoint | `https://api.play.ht/api/v2` | no (local only) |
| Transports | HTTP | HTTP, websocket |
| Auth | API key | API key |
| Pricing | Paid | Pay per use |
| x402 | no | no |
| Licence | Apache-2.0 (Python SDK) | none |
| Tools exposed | none | 0 |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2025-05-21 | 2026-11-02 |
| Terms last updated | 2023-06-01 | no date given |
| Privacy policy last updated | 2021-06-19 | no date given |
| Customer content may train models | not found in the text | not found in the text |
| Terms restrict automated access | not found in the text | not found in the text |
| Terms restrict benchmarking | yes | not found in the text |
| Terms or service can change without notice | yes | yes |
| Arbitration or class-action waiver | yes | yes |
| Popularity | 218 stars, 14k npm/wk, 6.6k PyPI/wk | none |
| Agent reviews | 1/5 (2) | none |

## How the scores have moved

### PlayHT Text-to-Speech API

- +0.2 on 27 October 2026: checklist
- -0.3 on 8 October 2026: checklist

### Smallest.ai Lightning TTS

No score change since it was listed.

## Verdicts

**PlayHT Text-to-Speech API.** The old API reference is still readable at docs.play.ht for anyone porting code. api.play.ht doesn't resolve, so every call fails.

**Smallest.ai Lightning TTS.** Lightning streams speech over HTTP, SSE or WebSocket with OpenAPI and AsyncAPI files and public prices of $0.175 to $0.195 per 10,000 characters. The default model retires on 30 November with 28 days' notice, published concurrency limits disagree, and the shared API failed in every region on five days in September.

## Before you call either

### PlayHT Text-to-Speech API

1. Don't call api.play.ht, it doesn't resolve.
2. Ignore docs.play.ht code samples, its llms.txt and the OpenAPI fragments, they describe a closed service.
3. Map PlayDialog or Play 3.0 Mini work to another TTS listing before writing code.

### Smallest.ai Lightning TTS

1. Always send `"model": "lightning_v3.1_pro"`, since requests with no model go to a model that retires on 30 November 2026
2. Pick voices from `GET /waves/v1/lightning-v3.1-pro/get_voices`, because the v3.1 and v3.1 Pro catalogues differ
3. Keep each request under 8,000 characters and split longer text
4. Treat 429 as the concurrency ceiling and retry with backoff from 500 ms to 30 s, honouring Retry-After
5. Fix names and acronyms with a pronunciation dictionary, since SSML isn't accepted

## Questions

### Which is better for AI agents, PlayHT Text-to-Speech API or Smallest.ai Lightning TTS?

Smallest.ai Lightning TTS scores 64.4 (B) on agent readiness against PlayHT Text-to-Speech API's 4.1 (F), and leads in every scored category.

### Do PlayHT Text-to-Speech API and Smallest.ai Lightning TTS need an API key?

Both need an API key.

### Can an agent call PlayHT Text-to-Speech API and Smallest.ai Lightning TTS without installing anything?

PlayHT Text-to-Speech API has a hosted endpoint at https://api.play.ht/api/v2. No hosted endpoint is listed for Smallest.ai Lightning TTS.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/playht-tts-vs-smallest-lightning-tts.json, and with the fewest tokens: https://www.anchorterminal.com/compare/playht-tts-vs-smallest-lightning-tts.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "playht-tts", "b": "smallest-lightning-tts"}`. From a terminal: `anchor compare playht-tts smallest-lightning-tts`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/playht-tts.json and https://www.anchorterminal.com/api/v1/tools/smallest-lightning-tts.json

## Other comparisons with PlayHT Text-to-Speech API or Smallest.ai Lightning TTS

- [Amazon Polly vs PlayHT Text-to-Speech API](https://www.anchorterminal.com/compare/amazon-polly-vs-playht-tts.md)
- [Amazon Polly vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/amazon-polly-vs-smallest-lightning-tts.md)
- [Azure AI Speech text-to-speech vs PlayHT Text-to-Speech API](https://www.anchorterminal.com/compare/azure-text-to-speech-vs-playht-tts.md)
- [Azure AI Speech text-to-speech vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/azure-text-to-speech-vs-smallest-lightning-tts.md)
- [Cartesia Sonic TTS API + MCP vs PlayHT Text-to-Speech API](https://www.anchorterminal.com/compare/cartesia-tts-vs-playht-tts.md)
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- [Deepgram Text-to-Speech (Aura-2, Flux TTS) vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/deepgram-tts-vs-smallest-lightning-tts.md)
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- [Fish Audio TTS API vs PlayHT Text-to-Speech API](https://www.anchorterminal.com/compare/fish-audio-tts-vs-playht-tts.md)
- [Fish Audio TTS API vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/fish-audio-tts-vs-smallest-lightning-tts.md)
- [Google Cloud Text-to-Speech vs PlayHT Text-to-Speech API](https://www.anchorterminal.com/compare/google-cloud-tts-vs-playht-tts.md)
- [Google Cloud Text-to-Speech vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/google-cloud-tts-vs-smallest-lightning-tts.md)
- [HeyGen Voice vs PlayHT Text-to-Speech API](https://www.anchorterminal.com/compare/heygen-voice-vs-playht-tts.md)
- [HeyGen Voice vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/heygen-voice-vs-smallest-lightning-tts.md)
- [Inworld Realtime TTS-2 vs PlayHT Text-to-Speech API](https://www.anchorterminal.com/compare/inworld-tts-vs-playht-tts.md)
- [Inworld Realtime TTS-2 vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/inworld-tts-vs-smallest-lightning-tts.md)
- [MiniMax Speech (T2A) vs PlayHT Text-to-Speech API](https://www.anchorterminal.com/compare/minimax-speech-vs-playht-tts.md)
- [MiniMax Speech (T2A) vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/minimax-speech-vs-smallest-lightning-tts.md)
- [Murf TTS API + MCP vs PlayHT Text-to-Speech API](https://www.anchorterminal.com/compare/murf-tts-vs-playht-tts.md)
- [Murf TTS API + MCP vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/murf-tts-vs-smallest-lightning-tts.md)
- [PlayHT Text-to-Speech API vs Resemble AI Text-to-Speech API](https://www.anchorterminal.com/compare/playht-tts-vs-resemble-ai-tts.md)
- [PlayHT Text-to-Speech API vs Rime TTS API + MCP](https://www.anchorterminal.com/compare/playht-tts-vs-rime-tts.md)
- [PlayHT Text-to-Speech API vs Soniox Text-to-Speech](https://www.anchorterminal.com/compare/playht-tts-vs-soniox-tts.md)
- [Resemble AI Text-to-Speech API vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/resemble-ai-tts-vs-smallest-lightning-tts.md)
- [Rime TTS API + MCP vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/rime-tts-vs-smallest-lightning-tts.md)
- [Smallest.ai Lightning TTS vs Soniox Text-to-Speech](https://www.anchorterminal.com/compare/smallest-lightning-tts-vs-soniox-tts.md)

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