Every PR reviewed.
Zero tests written.

DiffFence reads your diff, generates tests, runs them on both branches, and tells you exactly what broke. One command.

Understands your intent

DiffFence reads what you changed, infers why you changed it, and imagines what could go wrong. Then writes a test for each scenario.

Intent: Simplify input validation
Mutant: Forgot null check on currency parameter
Test: expect(validateCurrency(null)).toBe(false)

Tests to maintain

Generated on the fly. Discarded after use. Nothing to commit.

Self-healing

Wrong expected value? DiffFence reads the error, fixes the test, and re-runs. Real bug in old code? Flagged separately, never suppressed.

Low noise

Multiple layers of filtering strip out type errors, flaky assertions, and import failures. You only see real behavioral changes.

Works in CI

One line in your GitHub Actions workflow. Auto-detects PRs, posts review comments, returns exit codes.

- run: npx difffence ci --base main

Simple pricing.

No tiers. No credits. No confusion.

$ 2 / PR

Everything included. Pay only when DiffFence runs.

✓ Up to 30 functions analyzed per PRCovers even large pull requests
✓ Up to 200 lines per functionFull context for accurate analysis
✓ Auto-posts review comments on your PRInline comments with bug details and confidence scores
✓ Self-healing tests & noise filteringOnly real behavioral regressions surface
✓ Works with GitHub ActionsOne-click GitHub App install. Zero config.

Install GitHub App

No credit card required to start.

Bigger PR? Split it — it's better engineering anyway.
Need more? Contact us for enterprise.

No config. No test setup. Just run it.

$ npx difffence run --base main