Bug: 01/--
Lives: 3 lives left
Score: 0000
Best: --

Bug Hunt

Every snippet has one buggy line. Read what it should do, then tap the line that breaks it before the clock runs out.

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Bug Hunt

Express debugging: every snippet says what it should do, and exactly one line breaks it. Off-by-ones, = instead of ===, a missing await, text added to numbers… Tap the culprit before time runs out.

10 bugs
Python + JS

How to play

Read. The goal says what the code should do, with an example.
Spot. Tap the one line that breaks it. Only one line needs fixing.
Race. Faster answers and streaks score more. A wrong line costs a life.
Learn. Each round shows the fixed line and the bug pattern behind it.

Quick tips

Run the example. Mentally run the example from the goal through each line. The bug is where the value goes wrong.
Check the boundaries. <= vs <, range(n) vs range(1, n + 1): limits are where most bugs hide.

3 more tips in the Bug Hunt guide →