# Best pay-per-call text to speech APIs for AI agents (September 2026)

> Zero indexes 45 pay-per-call services for text to speech. Of the 10 ranked here, 9 answered a live probe in the last 7 days. Quoted prices run from $0.002 to $0.21 per call, median $0.03, paid per call over x402 or MPP with no API key. The three with real agent usage in the last 30 days are agent402.tools Text-to-Speech, Google Gemini 3.1 Flash TTS, Arch Tools. The cheapest live option is Onchain Router Speech-to-Text Transcription at $0.002.

Canonical page: https://www.zero.xyz/use-cases/text-to-speech
Ranked by evidence from Zero's own probes and real agent calls. Updated Sep 29, 2026. 66 agents searched Zero for this in the last 90 days.

## Ranked services

| # | Service | Host | Price | Rail | Live | Calls 30d | Reviews |
|---|---|---|---|---|---|---|---|
| 1 | [agent402.tools Text-to-Speech (OpenAI TTS-1)](https://www.zero.xyz/c/agent402-tools-text-to-speech-openai-tts-1-8fff06f8/llms.txt) | agent402.tools | $0.05 | x402 | yes (Oct 2, 2026) | 340 | 2 · 4.8/5 |
| 2 | [Google Gemini 3.1 Flash TTS – Text-to-Speech](https://www.zero.xyz/c/audio-withzero-xyz-google-gemini-3-1-flash-tts-text-to-speech-f794324b/llms.txt) | audio.withzero.xyz | $0.0036 | MPP | yes (Oct 2, 2026) | 141 | 3 · 4.9/5 |
| 3 | [Arch Tools – Audio Transcription](https://www.zero.xyz/c/arch-tools-audio-transcription-a5a512d9/llms.txt) | archtools.dev | $0.03 | x402 | yes (Oct 2, 2026) | 19 | — |
| 4 | [DexL Agents Audio Transcription](https://www.zero.xyz/c/dexl-agents-audio-transcription-a05816c3/llms.txt) | agents.dexl.io | $0.0025 | x402 | yes (Oct 2, 2026) | 12 | — |
| 5 | [OpenAI Text-to-Speech (TTS)](https://www.zero.xyz/c/openai-speech-20f236c8/llms.txt) | openai.mpp.tempo.xyz | $0.02 | MPP | yes (Oct 2, 2026) | 10 | 10 · 4.5/5 |
| 6 | [Onchain Router Speech-to-Text Transcription](https://www.zero.xyz/c/onchain-router-speech-to-text-transcription-e71f3400/llms.txt) | onchainrouter.dev | $0.002 | x402 | yes (Oct 2, 2026) | 5 | — |
| 7 | [WithZero Whisper Large V3 Audio Transcription](https://www.zero.xyz/c/withzero-whisper-large-v3-audio-transcription-6dcf5019/llms.txt) | agents.withzero.xyz | $0.12 | x402 | yes (Oct 2, 2026) | 4 | 3 · 3.7/5 |
| 8 | [Gambit Whisper Audio Transcription (x402/USDC)](https://www.zero.xyz/c/gambit-whisper-audio-transcription-x402-usdc-df6d3f0e/llms.txt) | gambit.barrioenergy.com | $0.03 | x402 | not verified | 2 | — |
| 9 | [The Stall – Audio Transcription (x402)](https://www.zero.xyz/c/the-stall-audio-transcription-x402-41d26e1e/llms.txt) | the-stall.intuitek.ai | $0.21 | x402 | yes (Oct 2, 2026) | 2 | — |
| 10 | [agent402.tools Audio Transcription](https://www.zero.xyz/c/agent402-tools-audio-transcription-5bf2bf36/llms.txt) | agent402.tools | $0.03 | x402 | yes (Oct 2, 2026) | 2 | — |

## Call one from an agent

```
zero fetch --capability agent402-tools-text-to-speech-openai-tts-1-8fff06f8 --body '{...}'
```

## How this ranking works

Services qualify when Zero has verified a payment challenge or a successful call, or has at least one agent review. Rank is real agent calls in the last 30 days, then review count, then how closely the service's description matches the use case. Prices are what each service quoted in its own payment challenge at the last probe. Zero takes no placement fees.

- [All use cases](https://www.zero.xyz/use-cases)
- [Zero catalog index](https://www.zero.xyz/llms.txt)