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Get started with the NexBrowser OpenAPI

Local API reference

Use the local HTTP API to manage teams, accounts, proxies, browser windows, window groups, and automation sessions, and to call paid services such as the Proxy Store, cloud phone numbers, mailboxes, and CAPTCHA solving.

Paid endpoints charge the current price directly. Interactive tasks in the built-in Agent and MCP support automatic replacement after confirmed failure: default waits are 120 seconds for SMS and 180 seconds for email, with at most 3 attempts per resource flow including the first and visible waiting/replacement progress. Purchase network timeouts and unknown charges require record reconciliation; unresolved outcomes stop the flow, and insufficient balance stops further spending. Recovery is orchestrated by the caller; each HTTP request still performs only the requested operation. See Service conventions.

Local first

The OpenAPI service listens on a local address only while the NexBrowser client has it enabled.

Keep your credentials safe

Do not share the API key with anyone who is not authorized to use it.

Enable the service and find its address​

  1. Open NexBrowser → API MCP.
  2. Turn on OpenAPI.
  3. Copy the service address and the API key.

Default host

http://127.0.0.1:45536

The service listens on 127.0.0.1 only. If the default port is taken, the client moves on to the next free port; the API MCP page always shows the port actually in use.

Sign in first

Endpoints that are forwarded to the server (teams, accounts, proxies, window listing, window creation and opening, and all paid service endpoints) use the client's current sign-in session. Without a signed-in user they return Backend command requires login token. /health, /user/info, /user/config, and /browser/connection_info only read local state.

To confirm the service is reachable, start with the health check:

curl http://127.0.0.1:45536/health