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

# Deprecation policy

> How we version the API and communicate breaking changes.

The Developer API is part of the NexRex [Data Portability
Promise](https://nexrex.ai/data-portability): if you build on it, we won't pull
the rug out from under you.

## Our commitment

* **Breaking changes are announced at least 90 days in advance**, except where a
  security or legal emergency requires an immediate change.
* We publish a version date on every response (`X-API-Version`, currently
  `2026-07-01`). A breaking change ships under a new version date; the previous
  version keeps working through the notice window.
* **Additive changes are not breaking.** New fields may appear on responses, and
  new endpoints may be added, at any time. Build your client to ignore unknown
  fields.

## What counts as breaking

* Removing or renaming an endpoint, field, scope, or error code
* Changing the type or meaning of an existing field
* Tightening validation in a way that rejects previously valid requests
* Reducing a rate limit

## Staying informed

Breaking-change notices are published on the [Data Portability
Promise](https://nexrex.ai/data-portability) page and its changelog. The
machine-readable [OpenAPI spec](https://api.nexrex.ai/api/v1/developer/v1/openapi.json)
always reflects the current version — diff it to see exactly what changed.

## Current limitations

This is v1. Some capabilities are intentionally not yet available:

* **Read and export only** — no write or propose endpoints, and no webhooks.
* **GPX / FIT / TCX** export formats are not yet offered (CSV and JSON today).
* Some raw vendor payloads may be restricted by the upstream provider's terms and
  are not included in exports.