codecrafters-io/build-your-own-x

Master programming by recreating your favorite technologies from scratch.

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Summary Information

Updated 24 minutes ago
Type:Curated List / Learning ResourceCategory(s):Programming Courses & BooksLearning & Resources
Added to GitGenius on June 21st, 2026
Created on May 9th, 2018
Open Issues & Pull Requests: 645 (+0)
GitHub issues: Enabled
Number of forks: 51,540
Total Stargazers: 548,319 (+8)
Total Subscribers: 6,869 (+0)

Repository Insights (GitGenius)

Median issue/PR response: 46.4 hours
Mean response time: 67.9 days
90th percentile: 113.6 days
Tracked items: 301

How this project is maintained

Roughly one issue in three opened in the past year never receives a reply. 100% of open issues come from outside the core team, so the backlog reflects real-world use rather than internal planning. 61% of tracked open issues have had no activity in three months, so the open count overstates what is actively being worked. Only 49% of issues opened in the past year have been closed. Three people close 75% of everything that gets resolved.

Charts & Analytics

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Issue Activity (beta)

Open issues: 124
New in 7 days: 2
Closed in 7 days: 0
Avg open age: 421 days
Stale 30+ days: 117
Stale 90+ days: 96

Recent activity

Opened in 7 days: 1
Closed in 7 days: 0
Comments in 7 days: 1
Events in 7 days: 1

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Detailed Description

The build-your-own-x repository is a curated collection of step-by-step guides and tutorials for recreating popular technologies from scratch. Hosted on GitHub by CodeCrafters, the repository serves as a comprehensive learning resource grounded in the philosophy that understanding requires the ability to build. The repository is written primarily in Markdown and functions as an organized index of external tutorials and guides rather than containing original implementation code.

The repository organizes tutorials across more than twenty major technology categories, each containing multiple language-specific implementations and learning paths. Categories include 3D Renderer, AI Model, Augmented Reality, BitTorrent Client, Blockchain and Cryptocurrency, Bot, Command-Line Tool, Database, Docker, Emulator and Virtual Machine, Front-end Framework, Game, Git, Memory Allocator, Network Stack, Neural Network, Operating System, Physics Engine, Processor, Programming Language, Regex Engine, Search Engine, Shell, Template Engine, Text Editor, Visual Recognition System, Voxel Engine, Web Browser, Web Server, and Distributed Systems. Within each category, tutorials are listed with their programming language and linked to external resources, allowing learners to choose implementations that match their preferred language or learning style.

The repository has demonstrated sustained growth and community engagement.

This cross-pollination suggests the resource serves developers across diverse technology stacks and experience levels.

The tutorial collection spans from foundational concepts to advanced implementations. For instance, the Blockchain and Cryptocurrency category alone contains implementations in multiple languages including Python, JavaScript, Go, Java, Rust, Kotlin, TypeScript, Ruby, Scala, Crystal, and ATS, with tutorials ranging from building a blockchain in under 200 lines of code to comprehensive guides on production-ready cryptocurrency systems. Similarly, the AI Model category includes tutorials on Large Language Models, Diffusion Models for Image Generation, and Retrieval-Augmented Generation systems, reflecting current trends in machine learning education.

The repository's classification as a programming project, computer science learning resource, and hands-on coding platform reflects its dual purpose as both an awesome-list style aggregator and a gateway to project-based learning. By linking to external tutorials rather than hosting implementations directly, the repository maintains focus as a discovery and navigation tool while directing learners to specialized resources maintained by their original authors. This approach allows the repository to serve as a comprehensive index covering the breadth of technologies developers might want to understand deeply through implementation.