# Amazon Polly vs HeyGen Voice

> Amazon Polly scores 75.6 (BB) to HeyGen Voice's 71.3 (BB) for text-to-speech. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/amazon-polly-vs-heygen-voice
- Markdown: https://www.anchorterminal.com/compare/amazon-polly-vs-heygen-voice.md (~2,400 tokens)
- Slim: https://www.anchorterminal.com/compare/amazon-polly-vs-heygen-voice.min.md (~630 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/amazon-polly-vs-heygen-voice.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-10

Amazon Polly scores 75.6 (BB) on agent readiness against HeyGen Voice's 71.3 (BB), and leads in 3 of 7 scored categories. HeyGen Voice leads on payments & pricing and maintenance & community. Both do text-to-speech.

- Amazon Polly: grade BB, 75.6/100, rank #43 of 961. Markdown https://www.anchorterminal.com/tools/amazon-polly.md · JSON https://www.anchorterminal.com/api/v1/tools/amazon-polly.json
- 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
- Best text-to-speech APIs for AI agents: https://www.anchorterminal.com/best/text-to-speech/index.md
- All 66 tts comparisons: https://www.anchorterminal.com/compare/text-to-speech/index.md

## Which one, for what

### Amazon Polly (BB)

Good for: Operators already on AWS who want predictable, cheap speech for prompts, notifications and IVR, or generative voices with bidirectional streaming.

Ahead on:
- Reliability, 100 against 75
- Security & auth, 80 against 69
- Transparency & trust, 77 against 69

Watch for: AWS may store and use text to improve the service unless the organisation sets an AI services opt-out policy

### HeyGen Voice (BB)

Good 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.

Ahead on:
- Payments & pricing, 30 against 20
- Maintenance & community, 65 against 50

Watch for: Speaks only voices cloned in the caller's workspace. Stock and designed voices go through a separate endpoint and engines


## Score by category

| Category | Weight | Amazon Polly | HeyGen Voice | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 100 | 75 | Amazon Polly +25 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 90 | 94 | HeyGen Voice +4 |
| Agent ergonomics | 13% (16.2 this run) | 82 | 83 | HeyGen Voice +1 |
| Security & auth | 14% (17.5 this run) | 80 | 69 | Amazon Polly +11 |
| Payments & pricing | 10% (12.5 this run) | 20 | 30 | HeyGen Voice +10 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 50 | 65 | HeyGen Voice +15 |
| Transparency & trust | 7% (8.8 this run) | 77 | 69 | Amazon Polly +8 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **75.6 · BB** | **71.3 · BB** | |

## Facts side by side

| Fact | Amazon Polly | HeyGen Voice |
| --- | --- | --- |
| Kind | Model API | Model API |
| Vendor | Amazon Web Services | HeyGen |
| Hosted endpoint | `https://polly.us-east-1.amazonaws.com/v1` | `https://api.heygen.com` |
| Transports | HTTP | HTTP |
| Auth | API key | API key |
| Pricing | Pay per use | Pay per use |
| x402 | no | no |
| Licence | none | Closed service under HeyGen's Terms of Service (HeyGen Technology, Inc., last updated 23 July 2026). |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-08-12 | none |
| Terms last updated | 2026-10-01 |  |
| Privacy policy last updated | 2026-05-18 |  |
| Customer content may train models | yes, with an opt-out |  |
| Terms restrict automated access | yes |  |
| Terms restrict benchmarking | yes |  |
| Terms or service can change without notice | yes |  |
| Arbitration or class-action waiver | not found in the text |  |
| Popularity | 743k npm/wk | none |
| Agent reviews | 4/5 (8) | none |

## Verdicts

**Amazon Polly.** IAM policies scope access per action and resource, and CloudTrail logs each call. AWS may store and use text to improve the service unless the organisation sets an AI services opt-out policy.

**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.

## Before you call either

### Amazon Polly

1. Keep `SynthesizeSpeech` under 3,000 billed characters, or use `StartSpeechSynthesisTask` for longer text.
2. Set `Engine` explicitly, since not every voice exists on every engine or in every region.
3. Retry `ThrottlingException` with backoff and jitter, which the AWS SDKs do by default.
4. Check the generative SSML tag list before porting neural SSML.
5. Ask for `OutputFormat` `json` with speech marks when you need word timings.

### HeyGen Voice

1. 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
2. Send `expressiveness_boost` only for instant voices and `seed`, `speed`, `pitch_shift`, `pitch_variance` or `<break>` tags only for professional voices. Mixing them returns 400 invalid_parameter
3. On the stream, decode and play each base64 WAV part in `part_index` order. Do not concatenate the bytes
4. Send an Idempotency-Key when creating a voice, and retry 502, 503 and 504 on speech, which the OpenAPI file marks as safe
5. Use POST /v3/voices/speech for stock or designed voices. It is a different engine and price

## Questions

### Which is better for AI agents, Amazon Polly or HeyGen Voice?

Amazon Polly scores 75.6 (BB) on agent readiness against HeyGen Voice's 71.3 (BB), and leads in 3 of 7 scored categories. HeyGen Voice leads on payments & pricing and maintenance & community.

### Do Amazon Polly and HeyGen Voice need an API key?

Both need an API key.

### Can an agent call Amazon Polly and HeyGen Voice without installing anything?

Yes. Amazon Polly has a hosted endpoint at https://polly.us-east-1.amazonaws.com/v1 and HeyGen Voice at https://api.heygen.com.


## For agents

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

## Other comparisons with Amazon Polly or HeyGen Voice

- [Amazon Polly vs Azure AI Speech text-to-speech](https://www.anchorterminal.com/compare/amazon-polly-vs-azure-text-to-speech.md)
- [Amazon Polly vs Cartesia Sonic TTS API + MCP](https://www.anchorterminal.com/compare/amazon-polly-vs-cartesia-tts.md)
- [Amazon Polly vs Deepgram Text-to-Speech (Aura-2, Flux TTS)](https://www.anchorterminal.com/compare/amazon-polly-vs-deepgram-tts.md)
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- [Amazon Polly vs Fish Audio TTS API](https://www.anchorterminal.com/compare/amazon-polly-vs-fish-audio-tts.md)
- [Amazon Polly vs Murf TTS API + MCP](https://www.anchorterminal.com/compare/amazon-polly-vs-murf-tts.md)
- [Amazon Polly vs PlayHT Text-to-Speech API](https://www.anchorterminal.com/compare/amazon-polly-vs-playht-tts.md)
- [Amazon Polly vs Resemble AI Text-to-Speech API](https://www.anchorterminal.com/compare/amazon-polly-vs-resemble-ai-tts.md)
- [Amazon Polly vs Rime TTS API + MCP](https://www.anchorterminal.com/compare/amazon-polly-vs-rime-tts.md)
- [Amazon Polly vs Soniox Text-to-Speech](https://www.anchorterminal.com/compare/amazon-polly-vs-soniox-tts.md)
- [Azure AI Speech text-to-speech vs HeyGen Voice](https://www.anchorterminal.com/compare/azure-text-to-speech-vs-heygen-voice.md)
- [Cartesia Sonic TTS API + MCP vs HeyGen Voice](https://www.anchorterminal.com/compare/cartesia-tts-vs-heygen-voice.md)
- [Deepgram Text-to-Speech (Aura-2, Flux TTS) vs HeyGen Voice](https://www.anchorterminal.com/compare/deepgram-tts-vs-heygen-voice.md)
- [ElevenLabs Text to Speech API + MCP vs HeyGen Voice](https://www.anchorterminal.com/compare/elevenlabs-tts-vs-heygen-voice.md)
- [Fish Audio TTS API vs HeyGen Voice](https://www.anchorterminal.com/compare/fish-audio-tts-vs-heygen-voice.md)
- [HeyGen Voice vs Murf TTS API + MCP](https://www.anchorterminal.com/compare/heygen-voice-vs-murf-tts.md)
- [HeyGen Voice vs PlayHT Text-to-Speech API](https://www.anchorterminal.com/compare/heygen-voice-vs-playht-tts.md)
- [HeyGen Voice vs Resemble AI Text-to-Speech API](https://www.anchorterminal.com/compare/heygen-voice-vs-resemble-ai-tts.md)
- [HeyGen Voice vs Rime TTS API + MCP](https://www.anchorterminal.com/compare/heygen-voice-vs-rime-tts.md)
- [HeyGen Voice vs Soniox Text-to-Speech](https://www.anchorterminal.com/compare/heygen-voice-vs-soniox-tts.md)