The LMNT API is a RESTful API at https://api.lmnt.com that provides programmatic access to LMNT's text-to-speech and voice cloning models.
New to LMNT? Start with the Getting started guide for a hands-on walkthrough, or jump straight to Generate speech for the most common endpoint.
Prerequisites
To use the LMNT API, you'll need:
- An LMNT account
- An API key
For step-by-step setup instructions, see Getting started.
Available APIs
The LMNT API is organized into the following groups:
- Speech API: Generate speech from text, with optional word-level timestamps.
- Speech Sessions API: Stream text in progressively and receive audio as it's synthesized — best for real-time applications.
- Voices API: Create, list, retrieve, update, and delete voices, including instant clones from your own audio.
- Accounts API: Look up usage and plan information for your account.
Authentication
All requests to the LMNT API must include your API key in the X-API-Key header.
| Header | Value | Required |
|---|---|---|
X-API-Key | Your API key from your LMNT settings | Yes |
lmnt-version | API version (e.g. 2025-09-25) | Yes |
If you're using one of the client SDKs, the SDK sends these headers for you. For API versioning details, see API versions.
Getting API keys
The API is made available via the LMNT Playground. You can use the Playground to try out our models in the browser and then generate API keys in Account Settings.
Client SDKs
LMNT provides official SDKs that simplify API integration by handling authentication, request formatting, error handling, and more.
Benefits:
- Automatic header management (
X-API-Key,lmnt-version) - Type-safe request and response handling
- Built-in retry logic and error handling
- Streaming support
- Request timeouts and connection management
For a list of client SDKs and their respective installation instructions, see Client SDKs.