Overview

How it works

• You install the diffy GitHub App on your account or an organization and choose which repositories it can see.
• When a pull request is opened, gets new commits, is reopened or is marked ready for review, GitHub tells diffy.
• diffy reads the change together with the code around it, your project's own documents and the .diffy.yaml of the repository.
• The model you set up writes the review: OpenAI, Anthropic, Google Gemini or OpenRouter, through your own API key.
• diffy posts one review on the pull request, as the app's bot: a summary, and a comment on each line that has a problem.

What gets reviewed

Every pull request on a repository diffy watches, with these exceptions:

• Drafts wait. They are reviewed when they are marked ready for review.
• Pull requests opened by bots, like Dependabot, are skipped.
• Pull requests that were already open when you added the repository are left alone. A newer commit on one of them is reviewed.
• Files that are not worth a review (lockfiles, build output, generated files) and anything you list under ignore.

What you bring

An API key from a model provider. diffy has no models of its own: your code goes to the provider you picked, with your key, and you pay the provider for what the reviews use. Keys belong to an organization, are stored encrypted and are never shown again. See Models and API keys.