> ## Documentation Index
> Fetch the complete documentation index at: https://browseruse-0aece648-larsen-v1-unified-docs.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Legacy APIs (v2, v3, v4)

> Older API versions, kept working for backwards compatibility. New projects should use the unified /api/v1.

<Warning>
  **These APIs are legacy.** They keep working — existing integrations will not break — but new projects should build on the unified [`/api/v1`](/cloud/quickstart). The v2/v3/v4 surfaces are frozen and will be sunset over time.
</Warning>

## What changed

The old API versioned the *whole* surface (v2 → v3 → v4), so every improvement forced a migration. `/api/v1` versions only the *agent* — platform resources (browsers, profiles, files, billing) are stable and shared, and each agent versions itself internally. See [Quickstart](/cloud/quickstart) and [Choose an agent](/cloud/choose-an-agent).

## Where old things live now

| Legacy                                                            | Unified `/api/v1`                                              |
| ----------------------------------------------------------------- | -------------------------------------------------------------- |
| `POST /api/v2/tasks`, `POST /api/v3/sessions` (the browser agent) | [`POST /api/v1/agents/browser-use/runs`](/cloud/run-a-task)    |
| `POST /api/v4/sessions` (the code + browser agent)                | [`POST /api/v1/agents/browsercode/runs`](/cloud/run-a-task)    |
| v2/v3/v4 session file handling                                    | [Files](/cloud/files) (one workspace model, all agents)        |
| v2 `keep_alive` / session-as-browser                              | automatic [browser lifecycle](/cloud/manage-browser) — no flag |
| PATCH-to-stop a browser                                           | [`POST /stop`](/cloud/stop-a-run) everywhere                   |

## Reference

The full endpoint reference for each legacy version is under the **Legacy API v4 / v3 / v2** tabs. Use them only to maintain an existing integration.

* **Skills** stay on `/api/v2/skills` — still supported, unchanged.
* **Backwards compatibility:** your existing `/api/v2`, `/api/v3`, `/api/v4` calls continue to work. Migrate to `/api/v1` when convenient, not urgently.