# Fokuus API versioning and deprecation policy

How the public Fokuus API, MCP server and NLWeb search are versioned, what can change without notice and how deprecation is announced at least 90 days ahead.

## Current versions

- REST API v1 at `https://fokuus.be/api/v1`: stable since 21 September 2026. The [OpenAPI document](https://fokuus.be/openapi.json)  is version 1.0.0.
- MCP server `fokuus-public-information` 1.0.0 at `https://fokuus.be/mcp`, supporting MCP protocol versions 2025-11-25, 2025-06-18 and 2025-03-26.
- NLWeb search `/ask` following NLWeb 0.55.

No version is currently deprecated.

## What can change within v1

New response fields, new endpoints, new optional parameters, new MCP tools and new pages in the catalog. These changes do not break clients. Ignore fields you do not recognise.

## What requires a new major version

Removing or renaming a field or endpoint, changing a type or tightening validation. Such a change ships under a new path, such as `/api/v2`. On the MCP server a changed tool gets a new name. The previous version keeps working for at least 90 days after the announcement.

## How deprecation is announced

- The `Deprecation` header (RFC 9745) with the deprecation date, on every response of the affected version.
- The `Sunset` header (RFC 8594) with the date the version stops working, at least 90 days after the announcement.
- A `Link` header with `rel="deprecation"` and `rel="sunset"` pointing to this page. It is already present on every API response.
- `deprecated: true` in the [OpenAPI specification](https://fokuus.be/openapi.json)  and a notice on this page and in [llms.txt](https://fokuus.be/llms.txt) .

After the sunset date a retired version answers 410 Gone with a JSON error that points to its successor.

## Limits

The quota policy is on every response in `RateLimit-Policy`: 120 requests per 60 seconds per IP address. If that policy changes, you will see it in that header and in the [API documentation](https://fokuus.be/en/docs/) .

## Changelog

- October 2026: `RateLimit-Policy` on every response, 429 with `Retry-After` and `RateLimit`, and `Link` references to this policy. Additive, no action required.
- 21 September 2026: REST API v1, MCP server and NLWeb search published.

[Developer start](https://fokuus.be/en/developers/)  · [API documentation](https://fokuus.be/en/docs/)  · [OpenAPI](https://fokuus.be/openapi.json)

[Bron](https://fokuus.be/en/docs/versioning/) · [Agentdocumentatie](https://fokuus.be/developers/)