Rust Cohort — Build a JSON Parser
Learn Rust by building something real
Move beyond syntax tutorials. In this 6-week cohort, you build your own JSON parser in Rust from scratch — covering enums, ownership, borrowing, error handling, FFI, and Python integration.
Price: €2,000 · Duration: 6 weeks · Format: Group cohort · Next start: April 20, 2026
A collaboration between belderbos.dev and Refactor Coaching.
Who is this for?
Developers comfortable with Python (or another language) who want to learn Rust through a real project. Not a "hello world" workshop — you'll build a parser that you benchmark against Python's json module.
Time commitment: ~10 hours per week.
Program overview
What you build, week by week
Setup & Tokenization
- Project setup with cargo
- Variables & mutability
- Basic types: String vs &str
- Testing with #[test]
- Build a JSON tokenizer
Types & Errors
- Enums & pattern matching
- Option<T> and Result<T, E>
- Error handling with ? operator
- Custom error types
- Parse primitive JSON types
Ownership & Borrowing
- Structs and impl blocks
- References: & and &mut
- Ownership vs borrowing
- Memory safety principles
- Structured parser with state
Collections & Recursion
- Vec<T> and HashMap
- Iterators and loops
- Recursive data structures
- Display trait for serialization
- Parse arrays & objects
Python Integration
- Foreign Function Interface (FFI)
- PyO3 Python bindings
- Cross-language memory management
- Build as Python extension
- Call Rust from Python
Polish & Optimize
- Performance measurement
- String allocation optimization
- Benchmark vs Python's json
- Documentation & examples
- Production-ready library
Tech stack: Rust (cargo, clippy, rustfmt), enums, ownership/borrowing, FFI, PyO3, #[test]
What's included
- Weekly group call with your coaches
- Code review via GitHub PRs — detailed, honest feedback
- Professional, portfolio-ready project on GitHub
- Structured 6-week curriculum
- Access to invite-only community
Your coaches
Jim Hodapp — Seasoned Rust developer, open source contributor, and software engineering coach with over two decades of experience. He's worked across the stack — from GNOME and Ubuntu to embedded systems and startups — and now mentors developers through Refactor Coaching to level up both technically and professionally. Whether you're new to Rust or ready to deepen your systems programming skills, Jim brings the perspective, structure, and guidance to help you grow.
Bob Belderbos — Developer coach and builder with 11 years at Sun/Oracle and 6+ years coaching developers to ship maintainable software. Co-founded Pybites and built Pybites Platform (400+ Python exercises) and Rust Platform (60+ Rust exercises). 100+ developers coached. Bob brings the Python perspective and coaches on bridging Python and Rust — including PyO3 integration, when to reach for Rust, and writing clean code in both languages.
What developers say
It's been a privilege being part of the Rust cohort — I genuinely enjoyed the work and the whole experience.
The hands-on approach made all the difference. Building something real made Rust click in a way that tutorials never could — and honestly, it's made me a better Python developer too.
I finished the parser last Thursday — my Rust implementation is only 0.8x slower than CPython's C and 10–12x faster than simplejson. Check it out: github.com/13hulk/rust-cohort
— Vikas Z.
This 6-weeks Rust cohort was awesome! Jim is an amazing and thoughtful teacher and mentor. He's great at helping me develop a mindset of mastering Rust. With Jim's friendly guidance, I successfully built a real world project to get experience about Rust's mental model, syntax and its ecosystem. The weekly code review was really insightful and helpful, Jim provided invaluable feedback on my code. Over several iterations he guided me to improve my code to succinct, clear, idiomatic Rust code. Cannot say enough good things about this Rust cohort!
— Ben L.
This has been hands down one of the best instructor-led courses I have done. Everything from the curriculum structuring to the methodology pushes you to learn and build smoothly from day one. The knowledge I generated set me up to continue learning more complex concepts of the language on my own and gave me a solid TDD ground for Rust projects.
— Victor S.
The Rust Cohort was a strong, concept-driven program. It helped me take ownership, mutability, error handling, and Rust's compilation model clear and practical. I left able to read real Rust, spot AI hallucinations, and apply the mental model at work. Great value for busy engineers.
— Tim F.
Frequently asked questions
Do I need Rust experience? No. You need to be comfortable programming in another language (Python is ideal). We start from Rust basics and build up through the project.
What if I fall behind? Sessions are recorded for catch-up. You also have async support from Jim and Bob throughout the week.
How much time per week? 6–8 hours including the live session, coding exercises, and building your parser.
Do we work solo or in teams? Solo work on your own parser, but you learn together. The group format creates accountability and peer support.
Will this help my portfolio? Yes — a JSON parser with FFI and Python bindings is a serious Rust project. Real commits, real tests, real benchmarks.
In 6 weeks, you'll think in two languages and write better code in both.
Not ready yet? Start with 60+ Rust exercises first.