Get an API Key

Using the Ultravox API requires an API key.

You can sign-up for a free account that comes with 30 free minutes for creating calls.

Base URL

The Ultravox API is available at https://api.ultravox.ai/api/.

API Keys

Ultravox API keys are 41 characters long and are made up of two alphanumeric parts separated by a period. The first part is 8 characters long and the second is 32 characters.

For example: Zk9Ht7Lm.wX7pN9fM3kLj6tRq2bGhA8yE5cZvD4sT

Throughout the docs we use aBCDef.123456 for brevity.

X-API-Key Header

When making API calls, pass your key in using the X-API-Key header.

You should never expose your API key to client code

If you really want to ignore this advice for a local demo, use the X-Unsafe-API-Key header instead at your own risk. It works the same way except that our server will allow it in CORS preflight requests.

Here’s an example showing how to use the fictional API key aBCDef.123456 to get a list of calls:

curl --request GET \
--url https://api.ultravox.ai/api/calls \
--header 'X-API-Key: aBCDef.123456'

Rate Limits

The Ultravox API includes safeguards to help maximize stability for all customers. Too many requests can trigger an error with status code 429.

API Limits

We restrict the number of API requests per second. We restrict at the account and API key level as follows:

  • Account: 500 requests per second
  • API Key: 200 requests per second

Call Concurrency Limits

Accounts can have five concurrent calls. That means any calls that have been created and that are not yet ended.

Contact us if you need higher call concurrency limits. Ultravox can scale to thousands of concurrent calls per account.

Playground

If you want to quickly experiment with prompts and voices, the fastest way to do that is in the Ultravox Dashboard.

You can also paste in an Ultravox API key throughout the API reference (look for “Authorization” and paste your key where it asks for X-API-Key) and test the REST API endpoints.