Cursor setup

Cursor can send its chat, agent and inline-edit requests to any OpenAI-compatible API. This guide connects it to Claudech. It takes about two minutes.

Before you start#

A paid Cursor plan. Cursor accepts custom API keys and custom models only on its paid plans. On Free or Hobby, Cursor rejects the key on its own servers and the request never reaches Claudech.
A Claudech API key. Create one under API keys. API access unlocks after your first purchase; any token package is enough.
The model ids you want. They are listed on Models and returned by GET /v1/models.

1. Check the key works#

Run this once before touching Cursor. If it returns a reply, the key and balance are fine and any later error is a Cursor setting.

curl https://api.claudech.com/v1/chat/completions \
  -H "Authorization: Bearer sk-..." \
  -H "Content-Type: application/json" \
  -d '{"model": "claude-opus-5-5", "messages": [{"role": "user", "content": "Say hello"}]}'

2. Enter the key and base URL#

Open Cursor Settings → Models.
Under OpenAI API Key, paste your Claudech sk-... key into the API Key field.
Switch on Override OpenAI Base URL and enter exactly https://api.claudech.com/v1: with /v1, without a trailing slash, nothing after it.

3. Add the model ids#

Cursor does not read the Claudech model list by itself, so add each model you want:

Scroll to the model list and type a Claudech model id in its search box, for example claude-opus-5-5.
Click Add Custom Model.
Repeat for any others: claude-fable-5-1, claude-opus-5, claude-sonnet-5.

The name must be exactly the Claudech model id and must not match one of Cursor's built-in models.

Text

Base URL : https://api.claudech.com/v1
API key  : sk-...
Models   : claude-opus-5-5, claude-fable-5-1, claude-opus-5, claude-sonnet-5

4. Send a first message#

Current Cursor versions have no Verify button; the key is checked on the first request. Open Chat, pick the Claudech model in the model picker and send a message. The request then appears on your Usage page with its tokens and cost.

What runs on Claudech#

Cursor feature	Served by
Chat with a Claudech model selected	Claudech
Agent mode, tool calls and multi-step edits	Claudech
Inline edits	Claudech
Tab completions	Cursor
Auto (Cursor's model router)	Cursor
Background agents	Cursor

Cursor calls the API from its own servers, so the base URL must be publicly reachable; a local proxy will not work. While the override is on, Cursor sends every OpenAI-format request to Claudech, including requests for Cursor's built-in OpenAI model names, which are served by your default Claudech model. Turn the override off to use Cursor's own models again.

Troubleshooting#

Symptom	Cause	Fix
"Invalid API key. Unauthorized User API key" and nothing on your Claudech Usage page	Cursor refused the request before contacting Claudech: a Free/Hobby Cursor plan, a model name that collides with a Cursor built-in, or a base URL that was not saved	Check your Cursor plan, re-enter the base URL, save, restart Cursor and start a new chat. If step 1 above works, Claudech is fine
Add Custom Model does nothing	The name matches one of Cursor's built-in models	Use the Claudech model id exactly, not a vendor model name
"Verification failed" or 401 on the first message	Trailing slash, missing `/v1`, or a space copied with the key	Use exactly `https://api.claudech.com/v1`; re-copy the key
`402 insufficient_balance`	Your balance is empty	Top up under Billing
Response says a different model ran	Cursor asked for one of its own model names	Select the Claudech model id in the picker; the `x-claud-model` response header names the model that ran
Long agent replies stop early	Cursor's timeout is shorter than the response	Ask for smaller steps, or use a faster model such as `claude-sonnet-5`

More tools, including Cline, Continue, Zed and Aider, are on Other tools. For Claude Code, see Claude Code setup.

Claudech is an independent service and is not affiliated with Anysphere, the maker of Cursor.