Guides

Short, practical fixes for bugs that software teams ship again and again. Each guide shows the broken pattern, the fix, and how to check it yourself.

• How to stop charging customers twice with Stripe

  Double clicks, retries after a timeout and repeated webhooks. Idempotency keys, a disabled pay button and webhook de-duplication, with a test.

• How to find and fix N+1 queries

  One query per row is fast with ten rows and times out with ten thousand. The fix in Prisma, Django, Rails, Laravel and SQL, and how to count queries in a test.

• Postgres migrations that lock your tables

  CREATE INDEX without CONCURRENTLY, SET NOT NULL on a big table and the lock queue: why a deploy can freeze checkout, and the safe versions.

• Snyk alternative for teams that ship every week

  A release check on every pull request, at one flat price per account. Price and focus side by side with Snyk, and when to stay with it.

• Semgrep alternative for teams that ship every week

  A release check on every pull request, at one flat price per account. Price and focus side by side with Semgrep, and when to stay with it.

• Aikido alternative for teams that ship every week

  A release check on every pull request, at one flat price per account. Price and focus side by side with Aikido, and when to stay with it.

• Zelsis vs CodeRabbit: five pull requests with planted flaws

  Both tools reviewed the same five pull requests, each with one flaw written down in advance. What each found, what each missed, and how a reviewer differs from a release check.

• How to test Supabase RLS before you ship

  Five Row Level Security mistakes that leak or block data, each with a bad and a fixed version and a quick manual test using the anon key.

• Supabase: can't delete user (foreign key violation)

  Why deleting a user fails with "Database error deleting user", and the migration that fixes it with ON DELETE CASCADE or SET NULL.

• Stripe charges 100x less: amount must be in cents

  Stripe amounts are integers in the smallest currency unit. How to convert prices safely and which currencies have no decimals.

• Check the code before you buy a SaaS app

  How to get access to the repository, which findings cost you money after the sale, and what to verify by hand before you pay.

More real examples: bugs we found in popular open-source repos.