Build your own grep

Implement a blazing-fast text searcher with regular expressions.

beginner
Regex
Automata
I/O
Performance

About this challenge

Move beyond using regex by implementing it. Explore NFAs/DFAs, efficient file traversal, and UX niceties that make search tools delightful.

What you will build

  • CLI search tool compatible with common grep flags
  • Regex engine (NFA/DFA) with character classes and quantifiers

What you will learn

  • Regex internals and finite automata
  • Efficient file scanning and buffering strategies

Getting started

There is no backend work wired yet. When enabled, you will be able to enroll, track progress, and earn badges for completing stages.

For now, explore the curriculum and prepare your environment.

  • Skim all stages to understand the scope
  • Decide your implementation language
  • Set up a project with tests and formatter