openreader/docs-site/docs/configure/tts-provider-guides/other.md
Richard R 34b94534cf docs(tts): clarify fallback voice set logic for OpenAI-compatible providers
Update documentation to specify that OpenReader uses the Kokoro voice set
for Kokoro models and the standard OpenAI voices for other models when no
voice listing endpoint is available. Improves clarity on provider fallback
behavior.
2026-06-09 11:00:51 -06:00

54 lines
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---
title: Other
---
Use any OpenAI-compatible TTS service with OpenReader, including self-hosted servers not covered by a dedicated guide.
## Requirements
Your service only needs an OpenAI-compatible speech endpoint:
- `POST /v1/audio/speech`**required**.
- Voice listing is **optional** and auto-discovered from `/v1/audio/voices`, `/v1/voices`, or `/v1/styles`. If none respond, OpenReader falls back to default voices — the Kokoro voice set for Kokoro models, otherwise the standard OpenAI voices (`alloy`, `echo`, `fable`, `onyx`, `nova`, `shimmer`).
The endpoint may return `mp3`, `wav`, `ogg`, or `flac` — OpenReader normalizes non-mp3 audio to mp3 automatically. An API key is optional.
Known compatible implementations: [Kokoro-FastAPI](./kokoro-fastapi), [KittenTTS-FastAPI](./kitten-tts-fastapi), [Orpheus-FastAPI](./orpheus-fastapi), [Supertonic](./supertonic).
## Setup
**Recommended (auth + admin): Settings → Admin → Shared providers**
1. Add a shared provider with type `custom-openai`.
2. Set `API_BASE` to your service base URL (typically ending in `/v1`).
3. Set API key if your service requires authentication.
4. Set a default model/voice supported by your backend.
**Legacy bootstrap seed (optional, first boot only):**
```env
API_BASE=http://your-tts-server/v1
# API_KEY=optional-key-if-required
```
**Or in-app via Settings → TTS Provider:**
1. Set provider to `Custom OpenAI-Like`.
2. Set `API_BASE` to your service's base URL (typically ending in `/v1`).
3. Set `API_KEY` if your service requires authentication.
4. Choose a model and voice supported by your backend.
See [TTS Providers](../tts-providers) for admin-shared vs per-user behavior.
:::warning TTS requests are server-side
`API_BASE` must be reachable from the **Next.js server**, not just the browser. In Docker, use container names or `host.docker.internal`.
:::
## Troubleshooting
If voices don't load, confirm the server is reachable from the Next.js runtime and that at least one of `/v1/audio/voices`, `/v1/voices`, or `/v1/styles` returns a valid response. If none do, OpenReader falls back to default voices — synthesis still works as long as `POST /v1/audio/speech` succeeds.
## References
- [TTS Providers](../tts-providers)
- [TTS Environment Variables](../../reference/environment-variables#tts-provider-and-request-behavior)