Perch

Some team conventions never fit a regular linter. "Refunds can only process once" or "store timestamps in UTC" depend on what the code means, not how it's formatted. Perch lets a code owner write rules like these in plain English in a perch.yaml file, each with a short name and an ensure line, and checks them on every change.

It parses the repository with tree-sitter and maps each method's callers and callees, so a changed method is read in context. Alongside your rules, it asks the same built-in questions of each changed method: is there a bug, is it a security hole, does it do what its name says, does it need refactoring. The docs show each finding with a confidence figure, such as 72%, which is the model's estimate that the problem is real. Those are leads for a reviewer, not verdicts.

The CLI installs from npm and is MIT-licensed on GitHub. According to the privacy policy, when it isn't connected to Perch Cloud it sends nothing to Perch, and your code goes only to the model provider you configure. That fits a check, fix and check-again loop after a coding agent edits files. The site lists Claude Code, Codex, Cursor, Pi and GitHub among the tools it works with.

Perch Cloud adds a pull request check that fails and comments on the flagged code. In that mode, the relevant source and rule questions go to TypeSafe, the model provider named in the privacy policy. Perch says it doesn't keep source after the analysis, though it keeps a one-way hash of each request with its answer so unchanged code can be served from the cache.

On October 24, 2026, hosted checks were priced at 10¢ per 1,000 rule checks, with cached checks free. The first $5 of usage is free and needs no card. The homepage estimates about 20¢ for a typical pull request where roughly 60 methods are read. Your cost depends on how many methods a change touches and how many rules you keep.