Windsurf

Codeium’s editor. Not every build accepts an outside key — first check whether it lets you edit the address at all.

Three fields. Copy, don’t type

Do it in order. Don’t skip

1. Open Windsurf → Settings (Cmd + , or Ctrl + ,).

2. Find the models section — it is called Cascade, Model Providers or Manage Models depending on the version.

3. Look for a provider marked OpenAI Compatible or Custom. Plain OpenAI won’t do: it has no editable address.

4. Base URL — from the card below, with the /v1 tail. API Key — your full key. Model — claude-opus-4.8.

5. Save, open a new Cascade chat, pick your model and type “hi”.

6. If there is no Base URL field anywhere, this build simply doesn’t take outside keys. Use Cursor, Cline or Roo Code instead — same three fields, and they always work.

Check

If it didn’t start

• Only a key field, no editable address — a build without custom-server support. That’s a Windsurf limitation, not your key.
• The model doesn’t show up — save the provider and reopen settings: Windsurf pulls the model list from our address.
• “401 / unauthorized / invalid api key” — the key was not copied whole. It starts with sk- and has no space at either end.
• “model not found” / “named models unavailable” / model in red — the name must match exactly: claude-opus-4.8. Not “Opus 5”, not opus, not claude-3, not gpt-4.
• The app shows no models — reopen its settings page: the model list is served from our address and appears once the Base URL and key are right.
• “Connection error” / spinner and silence — wrong Base URL. Almost every app wants the address with a /v1 tail.
• “/v1/v1” in the error — the app appends /v1 itself. Drop the tail, leave the site address.
• It replied, then stopped — you ran out of tokens. The balance is in your dashboard. Topping up on FunPay from the same nick lands on the same key.

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