Get your OpenRouter key
Takes about 2 minutes. You'll need a credit card for ~$1 in credits.
Faster option: on the main form you can click “Log in with OpenRouter” to authorize coarse and skip manual key creation. You still need an OpenRouter account with credits (steps 1 and 2 below), and we still recommend setting a per-key spend limit (step 4).
Create an account
Go to openrouter.ai and click “Get API Key” or sign up with Google / GitHub.
Add credits
Navigate to Settings → Credits. Add at least $10 — enough for ~10 reviews with an open-source model or 2 reviews with Claude. Unused credits don't expire.
Create an API key
Go to Settings → Keys, click “Create Key”, and name it coarse.
Copy the key now — you won't see it again.
Set a spending limit on the key
On the Keys page, click the ⋮ menu next to your new key and choose “Edit”. Again, we recommend setting a credit limit of at least $10. The key stops working once the limit is hit — zero risk of surprise charges — but set it high enough that a single review doesn't exhaust it, or the review will fail mid-run.
Why this matters: coarse is open-source — you can read every line of code. Your key is sent directly to OpenRouter to run the review, then discarded — it is never stored. But you don't have to trust us: the per-key limit guarantees it can never spend more than you allow, even in the worst case.
A note on cost estimates: coarse shows an approximate cost before each review (typically $0.25–$2). That's a heuristic with a ~15% buffer, not a hard ceiling. Actual cost can run up to ~2× the estimate on complex papers depending on how much the model reasons, how the critique agent rewrites comments, and whether proof-verification kicks in for math-heavy sections. If your per-key limit is set right at the estimate, a single review can drain it and fail mid-run. Leave headroom.
Paste into coarse
Come back here, paste your key into the form, and upload your PDF.