Daily Bug — Spot the Bug in Real Code
One real code snippet a day with exactly one bug. Click the line you think is wrong — five tries, no sign-up, and a result you can share.
One of these lines has a bug. Which one?
Loading today’s bug…
How it works
Every day you get a short piece of real code — JavaScript, Python, Go, SQL, Rust or Java — containing exactly one genuine bug: something that returns the wrong answer, crashes, or quietly corrupts data. Not a style nit. Click the line you think is wrong; you get five tries, and each guess tells you whether you hit the bug, landed in the right block, or missed entirely. Everyone in the world gets the same snippet each day, and the result you share says how you did without giving the answer away.
A puzzle for fun and for sharpening code review. The snippets are simplified to fit on a screen; real bugs are rarely this well lit.
Frequently asked questions
Do I need to know the language?
Rarely. The bugs are the ones every language shares — off-by-one, a missing await, comparing floats, a mutable default, a query without a WHERE. If you have written code in one language you will recognise most of them.
What counts as "the bug"?
Something that changes behaviour: a wrong result, a crash, a data-corrupting edge case or a security hole. Formatting, naming and style are never the answer.
Does everyone get the same snippet?
Yes. It is derived from the UTC date, so every player sees the same code on the same day and a new one appears at midnight UTC. The share grid is colours only, so posting it never reveals the line.