Not another LeetCode. bug.dr drops you into real production bugs with an AI assistant in your editor. You investigate, fix and verify, following career paths for your role. bug.dr scores how well you did it.
AI can suggest a fix in seconds. Knowing whether it's the right fix takes practice. On bug.dr, you work on bugs, making sense of the code, and checking that your changes solve the problem without creating another one.
Read the bug report and explore the codebase.
You'll know what the app is supposed to do and where it's failing. Finding the cause is your job. The timer starts when you start the case.
Use the editor, terminal, and AI assistant in your browser.
Follow a stack trace, ask questions, try a change, and run the code. Your prompts, token usage, and test runs are recorded along the way.
Run the checks when you're ready.
Your fix needs to solve the problem without breaking the rest of the app. Once you pass, your result is saved. You can't replay the same case to replace it with a better score.
Get the link in your inbox the day we open.
Join the waitlistStop guessing what to practice. Follow a path built around the work your target role actually involves, one well-solved problem at a time.
Models are only part of the job.
Practice the backend, data, and interfaces too.
STAGE 01 /
Trace a failure, make a focused change, and prove it works.
A prompt that exceeds the context window
An API response the client cannot parse
A vector search returning duplicate results
After each solve, get a debrief based on your session. See how many prompts, tokens, and test runs you used, how you compare with other people on that case, and what you could try differently next time.
It passes. What could I have done better?
You fixed it. Your change passed every acceptance check. The next thing to work on is how you get to the fix.
You ran tests 8 times before your first passing run. Next time, spend a little longer on the logs before asking AI for a change.
A working fix is the start. A repeatable approach is what you take into the next problem.
Generated automatically after every solve. Free tier includes feedback on Easy solves.
Choose your role and start with cases that fit your experience. Build confidence with easier fixes, then take on problems that need a deeper investigation.
Duplicate charges. Slow queries. Failed deployments. Browse by role, topic, and difficulty to find something worth working through. Every case includes a brief and the checks you need to pass, so you know what a working fix needs to do before you start.
Find your next case, keep track of your progress, or test yourself against the same challenge as other engineers.
Contests
Take on the same case. Daily, weekly, and monthly contests give you a shared challenge. See how your approach compares when everyone starts with the same problem.
Progression system
Every rank represents real engineering ability — not hours spent on toy puzzles. Debug your way from Intern to Principal.
You're finding your footing in real codebases.
You can read a stack trace and know where to start.
Production bugs slow you down, but they don't stop you.
Production incidents don't scare you anymore.
You see the system, not just the bug.
The rarest debuggers. You leave codebases better than you found them.
Start at the bottom. Climb by shipping fixes.
Free to start. Upgrade when you're serious.
€8.25/month · save €57 (36%) vs €155.88 billed monthly
Bring your Anthropic or OpenAI API key
Claude Opus · 150 prompts/day
Payments open after launch.
Be the first to pick a problem when the library opens.
Join the waitlistWe're opening bug.dr on October 21. Leave your email and we'll send you a reminder the night before and a link when it's live.
Yes. There's an AI assistant in the workspace. Use it to explore the code, ask questions, and work on your fix. You still need to understand the changes and check that they work.
They're practice codebases built around bugs and failures you could encounter at work. You get the context of a production incident in an environment where you can investigate and make changes.
The library covers cases using Node.js, TypeScript, Python, Go, React, Next.js, PostgreSQL, Redis, JWT, and WebSockets. Check each case for its stack before you start.
No. The editor, terminal, AI assistant, and tests run in your browser.
A working, reliable fix matters most. We also look at code quality, how you test your changes, time, and AI usage. Using fewer tokens or writing fewer lines doesn't automatically make a fix better.
Your first successful result is final. You can learn from it and take that experience into your next case.
Pro adds a personalized AI debrief after each solve and structured career paths. It costs €12.99 a month or €99 a year.
No platform can promise that. A path helps you build experience and see how your work compares with its benchmarks. Hiring decisions still belong to employers.
October 21, 2026. Join the waitlist and we'll send you the link when we open.
Yes. Join the waitlist and we'll reach out about using bug.dr with your team.
