About SystemCraft
SystemCraft is a free, open-source collection of high-level system design notes built for tech interview preparation.
What you’ll find here
Each design follows a consistent format:
- Understanding the problem — what the system does in plain English
- Naive first cut — the simplest possible design and why it breaks
- Prior art — real engineering blog posts and papers we draw from
- Functional & non-functional requirements — prioritized, not exhaustive
- Core entities & API — data model and interface
- High-level design — incremental component introduction with Mermaid diagrams
- Deep dives — Bad / Good / Great format for the hardest problems
- Core flows — sequence diagrams showing runtime interactions
Why this exists
These notes were created while preparing for system design interviews at top tech companies. The goal was a clean, structured resource that didn’t exist elsewhere — free, open-source, and always available.
Contributing
Found a mistake? Have a suggestion? Open an issue or PR on GitHub.
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