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

# Versioning

> What can change within v1, and how a change that removes something is announced.

The version is in the path: `/api/public/v1`. Within v1, changes are **additive only**:

* new endpoints,
* new optional parameters,
* new fields in HTTP responses and webhook payloads,
* new values where a field lists its values, such as a new event or a new error code.

To keep working through these changes, your code should ignore fields it doesn't know and treat an unknown value as "other".

Within v1, nothing is renamed or removed without notice. Anything that will go away is announced at least six months ahead.

## How a deprecation is announced

From the day of the deprecation, every HTTP response from the affected endpoint carries these headers:

| Header | Example | Meaning |
| - | - | - |
| `Deprecation` | `@1798761600` | The Unix time it was deprecated ([RFC 9745](https://www.rfc-editor.org/rfc/rfc9745)) |
| `Sunset` | `Sat, 03 Jul 2027 00:00:00 GMT` | When it stops working ([RFC 8594](https://www.rfc-editor.org/rfc/rfc8594)), at least 182 days later |
| `Link` | `<https://docs.usertick.com/changelog/developers>; rel="deprecation"` | Where to read about the change and what replaces it, when there is a note |

A client that logs a warning whenever an HTTP response has a `Deprecation` header learns about a change long before its sunset. Every deprecation is also listed in the [developer changelog](https://docs.usertick.com/changelog/developers.md).

No part of v1 is deprecated.

## Webhook payloads

A webhook delivery is `{ id, type, createdAt, data }`, where `data` is the [Response resource](https://docs.usertick.com/developers/api/response-object.md), or the spike on `theme.spiking`. These four keys stay the same within v1. New fields can appear in `data`, and new event types can be added, so a receiver should check `type`, or the `X-Usertick-Event` header, before handling a delivery.


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