$ show aradzie/keybr.com
This is a full-stack typing practice web application (keybr.com) built as a large TypeScript monorepo. The system provides adaptive typing lessons that track every keystroke, compute per-key statistics, and automatically generate lessons targeting the user's weakest keys. It supports dozens of keyboard layouts (QWERTY, Dvorak, Colemak, regional layouts, ergonomic layouts) and languages, with phonetic model-based word generation for practice text. The application includes a multiplayer typing race mode via WebSocket, user accounts with OAuth authentication (Google, Microsoft, Facebook), premium subscriptions via Paddle, and a theme designer for custom UI themes. The architecture is a monolith with server-side rendering (Fastr framework), a React 19 frontend bundled with webpack, a MySQL/SQLite database via Knex/Objection, and a separate WebSocket game server. The codebase is highly modular with over 50 packages covering UI widgets, charts, keyboard layout definitions, binary serialization, color science, math/statistics, internationalization, and code syntax generation for code-typing practice. While primarily an application, it also contains significant data/research components: phonetic model generation from word frequency dictionaries, statistical analysis of typing performance (learning rate, speed distributions, polynomial regression), and a C++ tool for validating user data files. The repository demonstrates high craftsmanship with clean abstractions, extensive test coverage, and reusable libraries that could be extracted for other projects.
The LLM identified 5 files worth highlighting for reuse:
A reusable binary Reader/Writer implementation with support for typed integers (8/16/32-bit signed/unsigned), floats, variable-length quantities (VLQ), length-prefixed strings, and strict bounds validation. The API is clean and self-contained, making it easy to extract for any project requiring efficient binary data serialization. Demonstrates careful attention to edge cases and performance.
Implements the OKLCH color model with conversions to/from RGB, OKLab, and other color spaces. Includes parsing, string formatting, and manipulation methods (lightness, chroma, hue). The implementation is mathematically rigorous and well-tested, showcasing non-obvious color science knowledge. Can be reused in any application needing modern color handling.
Provides polynomial regression fitting using a system of linear equations (SLE) solver. Includes methods for evaluating the fitted polynomial and computing R² goodness-of-fit. The implementation is clean, well-tested, and independent of the rest of the codebase, making it suitable for reuse in data analysis or machine learning projects.
A factory function for adding chart decorations (grid lines, axes, ticks, labels, no-data messages) to an SVG canvas. Uses a composable style injection pattern (`withStyles`) that separates decoration logic from rendering. The component is self-contained and can be extracted to build custom charting libraries with minimal effort.
Defines a domain-specific language for specifying programming language grammars using combinators like `ref`, `seq`, `alt`, `opt`, `cls`, `span`, and `flag`. The grammar rules are compiled into syntax trees for code-typing practice. This pattern is reusable for any project that needs to generate or parse language syntax definitions, and demonstrates a clean separation of grammar specification from execution.