---
title: "Versioning"
description: "Fluveo serves one API version, 2026-05-27.dahlia. Send no Fluveo-Version header."
url: https://docs.fluveo.com/start/versioning/
---

> Index of every page: https://docs.fluveo.com/llms.txt. Integrating Fluveo? Read https://docs.fluveo.com/agents/integrate.md first.

# Versioning

Fluveo serves one API version, 2026-05-27.dahlia. Send no Fluveo-Version header.

Fluveo serves one version of the `/v1` API: `2026-05-27.dahlia`. Every request is answered in that version, and every object and event has its shape. There is no older or newer version to choose.

The [deprecation policy](https://docs.fluveo.com/start/deprecation.md) says which changes can land inside this version and which need a new one, and the [changelog](https://docs.fluveo.com/changelog.md) lists each change by date.

## Send no Fluveo-Version header

You do not need to send the `Fluveo-Version` header. A request without it runs in `2026-05-27.dahlia`.

| You send | Fluveo answers |
| --- | --- |
| No `Fluveo-Version` header | The request runs in `2026-05-27.dahlia`. |
| `Fluveo-Version: 2026-05-27.dahlia` | The request runs in `2026-05-27.dahlia`. |
| `Fluveo-Version` with any other version, an older one such as `2024-06-20` included | `400` with `type` `invalid_request_error`, no `code`, no `param`, and the message `Invalid Fluveo API version: <the value sent>`. Nothing runs. |

## Events and webhook endpoints

Every event carries `"api_version": "2026-05-27.dahlia"`. When you create a webhook endpoint, its `api_version` parameter is optional. Any value other than `2026-05-27.dahlia` answers `400` with `param` `api_version`. See [Webhooks](https://docs.fluveo.com/webhooks.md).

## Copying code written for another payments API

Code written for another payments API often pins a different API version in a header, and SDKs send one on every request. On Fluveo such a request answers `400`. Remove the header, and call the API over plain HTTP instead of an SDK.

## Test it

1. Call `GET /v1/balance` with no `Fluveo-Version` header. You get `200`.
2. Check the `api_version` of any event in `GET /v1/events`. It is `2026-05-27.dahlia`.

> **For AI agents:**
>
> Send no Fluveo-Version header: every request runs in 2026-05-27.dahlia, the only version, and a Fluveo-Version that names another version is a 400 invalid_request_error with no code. Do not use an SDK: it sends its own version header.

## Next

- [Quickstart](https://docs.fluveo.com/start.md): Make your first test payment.
- [Authentication](https://docs.fluveo.com/start/authentication.md): Send your key on every request.
- [Deprecation policy](https://docs.fluveo.com/start/deprecation.md): See which changes need a new API version.
- [Changelog](https://docs.fluveo.com/changelog.md): Read what changed in the API and in these docs, by date.