> ## Documentation Index
> Fetch the complete documentation index at: https://docs.slng.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Unified API

The SLNG Unified API is a normalization layer across every speech model provider.

## The problem it solves

Every speech provider has its own way of doing things: own request format, own error handling, own parameters. And when someone wants to change an integration from Model A to B usually has to build and maintain a second new integration. That means one SDK per provider, different request formats, provider-specific error handling, and weeks spent evaluating each new model.

## How it works

You call a model available in SLNG gateway, and the Unified API translates it into whatever each provider expects, then translates the answer back.

* Authentication, request format, and responses stay the same across every model.
* To switch providers, you only change which model they point to.
* It covers both STT (speech-to-text) and TTS (text-to-speech).
* SLNG-hosted models and third-party models sit behind the same unification.

## What it unlocks

* **Freedom to switch.** New and better models become available as soon as SLNG adds them, with no upgrade work on the customer's side.
* **Easy testing.** Teams can send a share of their traffic to a different model to compare results, try new models in minutes, and fall back to another provider without changing how they handle errors.
* **No loss of control.** The Unified API lets you do anything. Settings like voice, language, audio format, and speed can still be passed through.

## Powers our 3rd party integrations

The Unified API also powers our integrations with the major voice agent frameworks. In LiveKit and Pipecat, developers name the model they want, and the [SLNG plugins](/integrations/plugins/livekit) connect through the Unified API automatically. Switching providers is a change to the model name, with no other code changes.

Get started quick with [this guide](/guides/models/unified-api).