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SeniorEng puts you inside real production incidents and pull requests.
Investigate systems, click through logs, read the diffs and find the bug.
Payment Service: Error rate 94% · 6 min ago
Your Move
Hint available · Score tracked
PR #4471: Add pagination to /orders endpoint
Medium · 15 minProblems
Train real-world engineering judgment.
Debugging Problems
How it works
You're paged in
An alert fires. Read the incident brief. What's down, what's burning.
Investigate on the left sidebar
Logs, metrics, traces, Slack threads, all on the left sidebar. The cause is buried in there. So are the red herrings.
Mitigate on the right panel
Take action on the right panel. Stuck? Use a hint. Your score tracks how fast you solved it, and whether you reached for the right lever.
Medium
YouTube, Gmail and GMeet Down
YouTube, Gmail, Meet, and Drive all went down at once. Inspired by a real incident.
Midnight Meltdown
Error rate jumps to 67% at exactly midnight.
Everything's Down. Nothing Looks Wrong.
503s across every endpoint, including login. Traffic is normal.
Hard
$440M in 45 Minutes
Market open 17 minutes ago. P&L is down $218M at $11M/minute. No errors. All 8 trading servers appear healthy. Inspired by a real incident.
Cache Errors. 18 Services Down.
18 unrelated services are all failing with cache errors. Memory is at 42%. Replication is fine.
Consumer Running. Events Dead.
The order-events consumer shows status: running. Restart count: 94. 8 downstream services have received zero events in 18 minutes.
Code Review Problems
How it works
Read the PR
A pull request just landed for review. Go through the changes, understand what's changing and why.
Spot the issues
Find the bugs, security holes, and performance traps hiding in the code. The left sidebar has context and Slack threads. Some issues are obvious. Most aren't.
Make your verdict
Approve, request changes, or block on the right panel. Hints available if you need them. Your score tracks what you caught and what you missed.
Easy
Medium
Adding Pagination
Review a critical pagination PR.
The Cascade Confusion
Review a critical perf enhancement PR.
SSL Certificate Verification Patch
Review a security patch to the TLS certificate verification function. Ships in tonight's release. Inspired by a real incident.
The Case History Search
Review a date-range search PR against a 50M-row table.
Multi-Currency Checkout
Review a currency conversion PR ahead of a major EU launch.
Referral Codes at Signup
Review a referral code system PR before a growth campaign launch.