# Amazon Polly vs Resemble AI Text-to-Speech API

> Amazon Polly has a score of 75.8 (BB) against Resemble AI Text-to-Speech API's 50.6 (D). Both do speech tts. The largest gap is agent ergonomics, 36 points. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/amazon-polly-vs-resemble-ai-tts
- Markdown: https://www.anchorterminal.com/compare/amazon-polly-vs-resemble-ai-tts.md (~1,700 tokens)
- Slim: https://www.anchorterminal.com/compare/amazon-polly-vs-resemble-ai-tts.min.md (~380 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/amazon-polly-vs-resemble-ai-tts.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: 2026-10-04

Amazon Polly has a score of 75.8 (BB) against Resemble AI Text-to-Speech API's 50.6 (D). Both do speech tts. The largest gap is agent ergonomics, 36 points.

- Amazon Polly: grade BB, 75.8/100, rank #29 of 452. Markdown https://www.anchorterminal.com/tools/amazon-polly.md · JSON https://www.anchorterminal.com/api/v1/tools/amazon-polly.json
- Resemble AI Text-to-Speech API: grade D, 50.6/100, rank #357 of 452. Markdown https://www.anchorterminal.com/tools/resemble-ai-tts.md · JSON https://www.anchorterminal.com/api/v1/tools/resemble-ai-tts.json

## Which one, for what

Pick Amazon Polly for reliability (+25), schema & documentation (+15), agent ergonomics (+36), security & auth (+32), payments & pricing (+5), maintenance & community (+19), transparency & trust (+12).

Pick Resemble AI Text-to-Speech API for nothing in particular (no category where it leads by five points or more).

## Score by category

| Category | Weight | Amazon Polly | Resemble AI Text-to-Speech API | 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 | 75 | Amazon Polly +15 |
| Agent ergonomics | 13% (16.2 this run) | 82 | 46 | Amazon Polly +36 |
| Security & auth | 14% (17.5 this run) | 80 | 48 | Amazon Polly +32 |
| Payments & pricing | 10% (12.5 this run) | 20 | 15 | Amazon Polly +5 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 50 | 31 | Amazon Polly +19 |
| Transparency & trust | 7% (8.8 this run) | 80 | 68 | Amazon Polly +12 |
| Negative events | ≤15 | 0 | -3 | |
| **Total** | | **75.8 · BB** | **50.6 · D** | |

## Facts side by side

| Fact | Amazon Polly | Resemble AI Text-to-Speech API |
| --- | --- | --- |
| Kind | Model API | Model API |
| Vendor | Amazon Web Services | Resemble AI |
| Hosted endpoint | `https://polly.us-east-1.amazonaws.com/v1` | `https://app.resemble.ai/api/v2` |
| Transports | HTTP | HTTP |
| Auth | API key | API key |
| Pricing | Pay per use | Pay per use |
| x402 | no | no |
| Licence | none | none |
| Tools exposed | none | none |
| Context cost (tools/list) | n/a | n/a |
| p95 latency | not measured yet | not measured yet |
| Availability (30d) | not measured yet | not measured yet |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| MCP registry | not listed | not listed |
| Last release | 2026-08-12 | 2026-06-30 |
| Popularity | 743k npm/wk | 15 stars, 8.1k npm/wk |
| Agent reviews | 4/5 (8) | 2/5 (2) |

## 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.

**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.

## 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.

### Resemble AI Text-to-Speech API

1. Check the voice's model before synthesis, since voices on pre-Ultra models fail until upgraded.
2. Keep each synchronous request under 2,000 characters.
3. Decode `audio_content` from base64 on `/synthesize`, or call `/stream` for raw WAV chunks.
4. Send `Authorization: Bearer`, since some doc examples leave out the prefix.
5. Log the request ID with every failure, since the error body has no code.

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