# Windsurf BYOK is locked. Use Xantly + Cline in VS Code instead.

**Direct answer:** Windsurf (Codeium's IDE) does not expose a custom base URL for its AI endpoints. Its "BYOK" toggle routes your Anthropic key through Codeium's hosted proxy to specific Anthropic models only, no OpenAI, no Groq, no custom gateways. If you hoped to plug Xantly in here, you can't. That's a product choice on Windsurf's side, not a limitation on ours.

This page exists so you don't burn an hour hunting for a setting that doesn't exist. Here's what actually works.

## What Windsurf's BYOK is and isn't

| What you might expect | What Windsurf actually does |
|---|---|
| Set a custom base URL like in Cline/Continue | Not supported. No UI, no env var, no config file flag. |
| Route through any OpenAI-compatible gateway | No. Locked to Codeium's own proxy. |
| Bring any Anthropic-compatible key | Only direct Anthropic account keys work. Gateway keys rejected. |
| Use GPT/Groq/Gemini via BYOK | Claude (via Codeium proxy) only. |
| Full Cascade + agent features with BYOK | Partial. Some agent flows still hit Codeium's internal models. |

## Why this matters for Xantly users

Xantly's value, smart routing across 10,000+ models, semantic cache, memory, waterfall fallback, BYOK on any provider, depends on having a custom base URL. Windsurf blocks the one setting that would make it work.

We've tested every published workaround (HOSTS-file spoofing, proxy interception, config-file edits). None of them survive a Windsurf update. The proxy URL is hard-coded and signed.

## What to do instead

### Option 1, Cline in VS Code (most similar experience)

[Cline](/docs/use-with-cline) is the closest Windsurf-Cascade equivalent with full Xantly BYOK:

- Cascade-style agent mode (Plan → Act → Verify).
- Multi-file edits.
- Tool calls to read/write files, run terminal.
- Full BYOK, any provider, any model.

The full setup takes 3 minutes. See the [Cline integration doc](/docs/use-with-cline) for the config block.

### Option 2, Continue.dev in VS Code / JetBrains

If you want Windsurf's "AI everywhere" feel (inline, chat, tab), [Continue.dev](/docs/use-with-continue-dev) splits LLM calls by role, chat, edit, apply, autocomplete, so you can route expensive roles through Xantly and free roles through a local Ollama model.

### Option 3, OpenCode CLI

If you're willing to leave the GUI IDE world, [OpenCode](/docs/use-with-opencode) is a first-class BYO story in 30 seconds.

### Option 4, Use Windsurf with direct Anthropic (no Xantly)

If you're committed to Windsurf specifically and happy with its Anthropic-only model selection, plug your direct Anthropic key into Codeium's BYOK. You won't get Xantly's benefits (routing, cache, memory, waterfall, multi-provider), but Windsurf will work. We can't help you here, this is an all-or-nothing situation on their side.

## "But Windsurf is so fast!"

Fair. Windsurf's Cascade UI is one of the slickest in the space. Cline catches up on features; Windsurf wins on polish.

If GUI polish is the deciding factor, try [Zed](/docs/use-with-zed), Rust-native, one of the fastest editors ever shipped, supports full custom OpenAI-compatible providers. Different flavor than Windsurf, but comparable on speed and fully Xantly-compatible.

## What we tell Windsurf users on our Discord

> "Windsurf's BYOK isn't real BYOK, it's Anthropic-only via their proxy. If you want Xantly's benefits (cross-provider routing, semantic cache, memory, waterfall fallback on any model), move your agent work to Cline in VS Code (same editor, same shortcuts, 3-min setup). Keep Windsurf around for side tasks if you like the UI."

## Will this change?

Maybe. Codeium-the-company shifted post-acquisition; a custom-provider feature would be a straightforward add. But we don't track their roadmap, and this page will update the week they ship it. Until then: use Cline.

## Next steps

- [Use Xantly with Cline](/docs/use-with-cline), the recommended migration.
- [Use Xantly with Zed](/docs/use-with-zed), if Windsurf's speed was the draw.
- [Migrate from Cursor](/docs/migrate-from-cursor), Cursor's BYOK has similar (but less severe) limitations.
- [Bring Your Own Key](/docs/bring-your-own-key), keep using your Anthropic/OpenAI credits through Xantly's routing.