Using Downsizing with Windsurf

Why Windsurf isn't supported yet

Windsurf does have a real BYOK feature for individual plans: in the model dropdown inside Cascade, models labeled BYOKlet you supply your own Anthropic or OpenAI API key instead of using Windsurf-hosted credits. The key is entered on Windsurf's own account page (windsurf.com/subscription/provider-api-keys), not in a local config file — there is no settings.json entry or extension setting that ds could template.

More importantly, that BYOK form only accepts an API key for a fixed, built-in provider (Anthropic or OpenAI) — there is no documented field for a custom base URL or an OpenAI/Anthropic-compatible endpoint. Requests still go straight to the provider's real API, just billed to your own key instead of Windsurf's credits. Without a base URL override, there is no way to point Cascade's model traffic at Downsizing's proxy.

Because we won't fabricate a config schema that hasn't been verified against real Windsurf behavior, we're not shipping a ds link windsurfintegration until Windsurf's BYOK flow (or a future settings surface) adds a documented, self-serve custom endpoint option.

What you can do instead

If you want Downsizing's cost savings today, check out our other supported integrations — most editors and CLIs that support a custom Anthropic or OpenAI base URL (Claude Code, Cursor, Cline, Goose, Codex, and more) work out of the box.

If Windsurf adds a documented custom-endpoint option for BYOK models in the future, we'll add first-class support here. If you have information about such a mechanism, please let us know.