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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, 399 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, 399 stages

Redis, Interpreter, Git, SQLite, DNS server, HTTP server, BitTorrent, grep, Shell, and Kafka.

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.