Chirp Audio API

The Chirp Audio API can generate an MP3/WAV file containing any suitable payload. The payload can be encoded using any of the available licences.


A Chirp payload is an array of bytes of a maximum length determined by the licence. For the audio API, payloads must be represented as a hexadecimal string. For example

[0, 1, 2, 3]  ->  00010203

[42, 100, 255]  ->  2a64ff


A list of available licences is available in the Chirp Admin Centre. The licence specification can also be found here, for example

48 bits [max] payload, and 2.529 seconds [max] duration.

For the audio API, all you need is the name of the licence.


For authentication, an application key / secret should be used as the username / password using Basic Auth. This can be retrieved from the Chirp Admin Centre. Here is an example using cURL.

curl -u <key>:<secret> -o chirp.mp3

In a web browser, you will be prompted to enter your credentials by the default Basic Auth pop up. Enter your application key / secret into the fields for username / password.


This has mixed support but credentials can also be passed in the URL like so

GET https://< key >:< secret >

API Reference

The Audio API is hosted at, and has the following endpoints.

Contains a random payload using the default licence for the application

Contains a random payload using the ultrasonic licence

Contains a specific payload of [42, 100, 255] using the standard licence

The Audio API returns MP3 files by default, but can also return WAV files.

Returns a WAV file containing a specific payload using the default licence

The Audio API will also return a wav file if the Accept header is set to audio/wav

The Audio API can also return some info on the specified licence, including the duration of a chirp in seconds, and the maximum payload length.

Returns the duration and max payload length of a random payload using the default licence.

Returns the duration and max payload length of a random payload using the default licence.

Postman Example

You can download a Postman collection which highlights the features of the Audio API here Audio API for Postman

We recommend using Insomnia REST client, a fantastic alternative to Postman, which allows you to preview the audio directly in the app.

Note: These example requests will require you to fill in the basic auth credentials. Fill in the username / password with your application key / secret.