Build your own developer tools

Build Your Own Text Editor (viewsourcecode.org) · Paige Ruten

A booklet that rebuilds antirez’s kilo editor in 184 small steps: raw terminal mode, reading keys, drawing the screen with VT100 escape codes, a row buffer, editing, saving, incremental search and syntax highlighting. About 1,000 lines of C in one file, no libraries, not even curses. You can compile and run after almost every step.

Read alongside: antirez’s own post on writing the original, Writing an editor in less than 1000 lines of code, just for fun (773 points, submitted 8×), and his source. “Reading through this code is a veritable rite of passage. You learn how C works, how text editors work, how VT codes work, how syntax highlighting works, how find works, and how little code it really takes to make anything when you strip away almost all conveniences, edge cases, and error handling.” (90s_dev, 2025 · comment)

Alternative in Rust: Philipp Flenker’s hecto (155 points) rebuilds the same editor in about 3,000 lines of Rust. “The step-by-step format using code diffs made everything very clear and easy to follow along.” (mblode, 2021 · comment)

Git from the inside out (maryrosecook.com) · Mary Rose Cook

Read this before writing any code. It runs a short series of Git commands on one small project and shows, after each, what changed in the .git folder: blobs, trees, commits, refs and the index. By the end you have the model the next step implements.

Write yourself a Git (wyag.thb.lt) · Thibault Polge

Build wyag, a Git that reads and writes real Git repositories, in about 1,000 lines of standard-library Python. You implement init, hash-object, cat-file, log, ls-tree, checkout, show-ref, tag, rev-parse, ls-files, check-ignore, status, rm, add and commit. The author notes that a commit in the tutorial’s own history was made by wyag itself. Check your work by running real git against the repositories your version writes, and the other way round.

HN’s comments point to a paid book that goes further: James Coglan’s Building Git, which also covers diffs, merges and the network protocol (comment).

Alternative: Nikita Leshenko’s ugit (667 points, submitted 4×) builds a Git-like tool in Python one small diff at a time, starting from init, with the code downloadable at every step. “I particularly like the iterated development approach to teaching on this site.” (mixedmath, 2021 · comment)

Build Your Own Redis with C/C++ (build-your-own.org) · James Smith

A Redis-like server built up from sockets: a TCP server and client, a request-response protocol, non-blocking IO with an event loop, then the data structures that make Redis fast (a resizable hashtable, a balanced binary tree, sorted sets), timers, key expiry with TTLs and a thread pool. If sockets are new to you, do step 1 of the networking course first; the book itself recommends Beej’s guide.