For modern devs who want to level up by building what they usually import.
π Why Build Your Own X?
You use databases, caches, languages, compilers, and tools every day. But have you ever tried building one?
Hereβs why you should:
- π§ Master the internals that make great software work
- π‘ Become a better systems designer & problem solver
- π§° Impress in senior interviews (FAANG+ loves this)
- π‘οΈ Stop treating tools as black boxes
- π Build deep, transferable skills that scale across tech stacks
π’ TL;DR: Donβt just learn frameworks. Learn to build the things frameworks are built on.
π§ What Can You Build?
Letβs break it down into actual "X" systems and provide step-by-step paths, codebases to fork, and resources to master each one.
π§ 1. Programming Language / Interpreter
Want to understand how Python, JavaScript, or Lua works under the hood?
β What Youβll Learn:
- Lexers, Parsers, ASTs
- Interpreters vs Compilers
- Memory models & VMs
π Learn:
π¦ Clone/Fork:
π₯ Challenge: Write your own scripting language for config files or templating.
π’οΈ 2. Database Engine
Time to ditch ORMs for a bit and build the engine they talk to.
β What Youβll Learn:
- B-Trees, WALs, Indexing
- Query planning
- Data on-disk formats
π Learn:
π¦ Clone/Fork:
π₯ Challenge: Build a SQL subset engine with SELECT/INSERT + B-Tree indexing.
β‘ 3. In-Memory Cache (like Redis)
Learn how Redis manages blazing-fast data access.
β What Youβll Learn:
- Serialization
- Expiry/TTL
- Pub-sub and persistence
π Learn:
π¦ Clone/Fork:
π₯ Challenge: Implement LRU, TTL, and pub-sub in your cache.
π 4. Web Framework
Skip Flask and Spring for now β build one from scratch.
β What Youβll Learn:
- HTTP handling, routers
- Middleware pipelines
- Templating engines
π Learn:
π¦ Clone/Fork:
π₯ Challenge: Build your own micro web framework with router, middlewares, and sessions.
π 5. Search Engine (like Google)
Learn the guts of full-text search and ranking.
β What Youβll Learn:
- Tokenization
- Inverted indexing
- Ranking algorithms (BM25, TF-IDF)
π Learn:
π¦ Clone/Fork:
π₯ Challenge: Build a mini search engine for markdown docs.
π³ 6. Container Engine (like Docker)
Learn the Linux syscalls that isolate processes.
β What Youβll Learn:
- Namespaces & cgroups
- Filesystems & image layers
- Kernel interactions
π Learn:
π¦ Clone/Fork:
π₯ Challenge: Build a basic isolated process runner with chroot
& namespaces.
βοΈ 7. Distributed System / Cloud Storage
Build the backend guts of Dropbox, Raft, or S3.
β What Youβll Learn:
- Leader election, consensus
- Fault tolerance
- Replication and partitioning
π Learn:
π¦ Clone/Fork:
π₯ Challenge: Implement a basic Raft consensus engine in your language of choice.
π§ Bonus: Other βXβ You Can Build
System | Resource |
---|---|
OS from Scratch | https://os.phil-opp.com/ |
Git clone | Write yourself a Git |
Docker clone | Build Your Own Docker |
React clone | Didact (JS) |
CLI tool | Cobra (Go) |
π§ How to Approach Building X
πΊοΈ Step-by-Step Blueprint:
- Pick one category (cache, DB, etc.)
- Follow one foundational tutorial
- Clone one production-grade repo
- Rebuild the core logic yourself
- Add one stretch feature (e.g., CLI, metrics, tests)
- Write a blog or record your learnings
π‘ Pro Tips:
- Use tests to validate logic
- Scope it down β no need to re-implement Redis entirely
- Stick to one language per project
- Document as you go
π§° Toolbelt for Builders
- π΅ Languages: Rust, Go, C, Python, JavaScript
- βοΈ Libraries:
gRPC
,LevelDB
,NATS
,LLVM
- π Debugging:
strace
,lsof
,gdb
- π Testing:
benchstat
,go test -bench
,pytest
π GitHub Playgrounds to Watch
- β danistefanovic/build-your-own-x
- β codecrafters-io β Professional-grade challenges for Redis, Git, etc.
- β awesome-selfhosted
π 6-Month Self-Learning Path
Month | Project | Focus |
---|---|---|
1 | JSON Parser / Lisp Interpreter | Parsing, AST |
2 | Key-Value Store | Memory, Serialization |
3 | SQL Engine | Indexing, Disk I/O |
4 | Web Framework | HTTP, Routing |
5 | Docker/Container | Isolation, syscalls |
6 | Consensus System | Raft, Replication |
π§ Final Words
π₯ "Great developers donβt just use tools β they understand how to build them."
If youβve ever installed a package with zero idea how it works: this is your chance to flip that.
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