# Versioning

The major version is in the path: every endpoint starts with `/v1`. Changes inside v1 add things; they do not break what you built.

Source: https://inplan.io/docs/versioning · Updated 2026-10-30

## What can change inside v1

- New endpoints, new optional parameters and new response fields.
- New values in `notes`, and new problem types for new kinds of errors.
- Wording of `title`, `detail` and `explanation`. Branch on `type` and `answer`, never on text.

Write clients that ignore fields they do not know. A change that would break a v1 client ships under a new path, such as `/v2`.

## Follow the changes

The [changelog](https://inplan.io/changelog) lists every change. `/openapi.json` always describes the API that is running, and `GET /v1/status` returns its build in `data.version`.