voice and config,
so you can integrate once and compare models more easily.
Why use it
Use the Unified API when you want to evaluate models, keep a fallback model, or route
calls to a different region without rebuilding the request for each provider. Use the
direct endpoints when you need a model’s provider-native parameters.
Swap models by changing the URL
Unified requests usehttps://api.slng.ai/v1/bridges/unmute/{tts|stt}/{model-id}.
The model ID is the final part of the path. It determines which provider and model
receives the call.
slng/ identifies a model hosted in your region. A model ID without that prefix is
proxied to the provider. See Which models are available
for the available routes, regions, and model IDs.
Make a request
All requests use your API key as a bearer token. For regional routing, replaceapi.slng.ai with {region}.api.slng.ai. See
Using regions in the services. If you
need a key, see Create your API key.
Synthesize speech
Send text and a normalizedvoice value. The field name stays the same when you switch
models, but the voice value must belong to the selected model. This request writes the
binary audio response to hello.wav.
Rime Arcana 3
Deepgram Aura 2
Transcribe audio
Send a recorded file as multipart form data. The response is a JSON transcript. See Unified STT for the response schema.Deepgram Nova 3 English
The model comes from the URL path. Do not send a duplicate
model field unless the
endpoint reference requires it.Stream with WebSocket
Use the same path with thewss:// scheme when you need to stream audio or text. The
Unified API uses the same WebSocket protocol as the direct endpoints. See
WebSockets vs HTTP for when to use each transport,
and Unified TTS over WebSocket for
the endpoint details.
The browser WebSocket API cannot send custom authorization headers. Authenticate from a
server-side WebSocket client, or use the query-parameter method documented by the
endpoint reference.
Unified or direct
Both API styles call the same categories of models. This table compares the endpoint and fields. Choose based on how much of the provider’s request format you need.
Start with Your first request if you are calling a
single model and need its native options. Use this guide when you want one integration
that can support several models.
Supported parameters
The Unified API accepts shared fields. A selected model still determines which voice names, language codes, encodings, and sample rates it accepts.Text to speech
Speech to text
The request shape stays the same, but provider support varies. Check the
Unified STT reference and the
selected model’s reference before you rely on an optional field.
Next steps
- Which models are available to find model IDs and routes.
- WebSockets vs HTTP to choose a transport.
- Unified STT and Unified TTS references for parameter coverage.
- Bring your own key to use a provider account.