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

# API versions and changes

> How the Signal API is versioned, which changes can happen within a version, and how we tell you before an older version stops working.

Last reviewed 9 November 2026

The Signal API puts its version in the path: every endpoint today starts with `/v1/`. Code written against `/v1/` keeps working for as long as `/v1/` exists.

## Changes within a version

Within a version we only make changes that existing code can safely ignore:

- New endpoints.
- New optional request fields and query parameters.
- New fields in responses. Your code should ignore fields it does not know.
- New metrics, filters, brands and periods on a DataSet. These are data, not part of the API contract.
- New values in fields that name a type or status, such as a new error code. Your code should accept values it does not know.
- Corrections to descriptions and documentation.

## Changes that need a new version

These changes come only in a new version, such as `/v2/`, never within one:

- Removing or renaming an endpoint, a field or a parameter.
- Making an optional field or parameter required.
- Changing the type or meaning of a field.
- Changing how errors are reported.

An endpoint marked **Deprecated** in the reference still works in its version. It is left out of the next one.

## When a new version is released

- Both versions run side by side. The older one keeps working for a period after the new one is released, and we tell you in good time before it stops working.
- We tell you by email to your organization's administrators and with a notice on this site, both when a new version is released and before an older one stops working.
- The API reference shows the current version. Choose an older one in the **API version** list at the top of each reference page.

## Where changes are listed

Every change to the API is listed with its date in the [API changelog](https://docs.odysseysignal.com/api/api-changelog).