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byox
byox

byox

Complete CodeCrafters "Build your own X" courses entirely locally, in Go — driven by the exact same official testers the real platform runs.
Get started Browse the catalog View on GitHub

Pick a course, write the stage, save — the official CodeCrafters tester runs locally and every earlier stage re-runs with it. 10 courses, 390 stages, no account.

What is byox?

Section titled “What is byox?”

byox is a single-screen TUI + engine that drives the official open-source course testers from CodeCrafters — the exact same checks the real platform runs — entirely on your machine, with stage-by-stage progress tracking. No account, no submission queue.

10 courses

Redis, Kafka, Git, SQLite, DNS server, HTTP server, BitTorrent, grep, Shell, and a tree-walk Lox Interpreter.

Official testers

Every stage is checked by the same open-source tester binaries CodeCrafters itself runs — not an approximation.

Reference solutions

Every course ships complete, tester-verified Go reference solutions, snapshotted stage by stage — browse them in the catalog.

Watch mode

Rustlings-style: save a file, the current stage’s tests run automatically and stream into the log pane.

Start in three commands

Section titled “Start in three commands”
Terminal window
git clone https://github.com/madhank93/build-your-own-x && cd build-your-own-x
mise install
just setup

See Getting started for the full setup.