Using Downsizing with Cursor

Prerequisites

Install the Downsizing CLI — see the CLI guide if you haven't already.

Link Cursor (Recommended)

Cursor's model-provider credentials (API key + "Override Base URL") live in its own internal application state, not a plain config file — there is no documented, stable on-disk settings file for this the way there is for e.g. VS Code's settings.json. So ds link cursordoesn't edit any files. Instead it prints the exact values to paste into Cursor's Models settings:

ds link cursor

Copy the printed values into Cursor's settings:

• Open Cursor, press Cmd/Ctrl + , to open Settings, then click Models
• Add your Anthropic API Key (the printed Downsizing API key)
• Enable "Override Anthropic Base URL" and paste the printed base URL
• Select a Claude model, e.g. claude-opus-4-8

If you'd rather use OpenAI-style routing, Cursor's Models page also has an "Add OpenAI API Key" / "Override OpenAI Base URL" pair — ds link cursor prints both sets of values, so use whichever fits your setup.

Important limitation

Per Cursor's own documentation, the custom API key / base URL override only applies to the chat / plan side panel. Cursor's Agent mode, Composer, inline edit, and Tab/autocomplete always route through Cursor's own backend and cannot currently be redirected to an external endpoint — this is a limitation of Cursor itself, not of Downsizing's proxy. Cursor's separate terminal tool, the cursor-agent CLI, has its own config file at ~/.cursor/cli-config.json, but that schema only covers editor/permissions/sandbox settings — it has no custom-endpoint or API-key field, so it can't be routed through Downsizing either.

Manual Setup

You can configure Cursor manually without running the CLI. Open Cursor's Settings → Models and fill in:

https://api.downsizing.dev/YOUR_ROUTER_ID/anthropic

Enter this as the base URL under "Override Anthropic Base URL", your Downsizing API key (starts with dws_) as the Anthropic API Key, and pick a Claude model, e.g. claude-opus-4-8.

Find your Router ID and API key on the Inference API page.

Verify

Open Cursor's chat/plan panel and send a message to confirm traffic is routing through Downsizing. If Cursor responds normally, Downsizing is set up correctly. You can also check your savings dashboard to see the request appear in your usage metrics.

Unlinking

Because ds link cursornever wrote a config file, there's nothing on disk to remove. Run the unlink command to update ds's own record of linked tools, then clear the API key/base URL fields directly in Cursor's Settings → Models:

ds unlink cursor