I gave myself 48 hours to validate an AI code review tool. Here's how I built it.

I wanted to test a simple idea: what if every pull request you opened got an instant AI code review? Not a replacement for human reviewers — just a first pass that catches the obvious stuff before your teammates even look at it. So I gave myself 48 hours to build it, ship it, and see if anyone actually finds it useful. What it does CodeReview.ai is a GitHub App. You install it on a repo, and every time a PR is opened, it: Receives a webhook from GitHub Pulls the diff via the GitHub API Sends it to GPT-3.5-turbo with a code review prompt Posts the review as a PR comment within seconds That's it. No dashboard, no config files, no pricing tiers. Install and go. The stack TypeScript end to end Vercel serverless functions for the webhook handler Octokit for GitHub API calls OpenAI API (GPT-3.5-turbo) for the review PostHog for tracking installs and usage Static HTML + Tailwind for the landing page The whole thing is two API routes: one for the GitHub webhook, one for waitlist signups. What