Nikos Baxevanis
I build tools that catch deep bugs in critical systems before they go live. At the Stacks Foundation, I developed fuzzers and model-based testing tools that flagged consensus issues and denial-of-service vectors ahead of a major network upgrade. I maintain foundational testing libraries like Hedgehog, which powered Echidna, the first smart-contract fuzzer for Ethereum. My background spans Haskell, F#, .NET, Rust, and TypeScript, with a focus on input shrinking, reproducible failures, and execution instrumentation.
Projects
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2022 – present
Core contributor to rendezvous and madhouse-rs, fuzzing tools for Clarity and Rust. Helped identify issues during network upgrade testing and chain behavior under load. -
2016 – present
Core contributor to Hedgehog — property-based testing for Haskell, F#, R, and Scala. Used in the early development of Echidna by Trail of Bits. -
2017 – 2020
Ported SplitMix — a fast splittable PRNG. Based on work by Steele, Lea, and Flood. Passes all dieharder tests. Used in Hedgehog for replay and shrinking. -
2011 – 2020
Ported dk.brics.automaton and xeger to create Fare — a library for generating regex-constrained strings. Used in AutoFixture and widely adopted as an alternative to Microsoft's Rex. -
2011 – 2016
Core contributor to AutoFixture, a .NET testing library (3.5k+ stars). Helped shape AutoFixture 3, introduced novel features and tools like Fare. Project later submitted to the .NET Foundation.
Writing
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2023-01-30 – Invariant testing from command-line
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2022-03-15 – Clarity model-based testing primer
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2022-03-05 – Clarity property-based testing primer
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2020-03-30 – The rhyme of the altered parser
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2017-04-10 – Less fragmented properties with Hedgehog
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2016-02-08 – Write you some QuickCheck
What others say
“One of the best developers I've ever worked with is @nikosbaxevanis. Please don't steal him from my team!”
—Mark Seemann, author of Dependency Injection Principles, Practices, and Patterns
“Solid development skills. When Nikos submits a pull request, it is a cold day in hell that it doesn't work.”
—Kevin Bennett, co-founder and CTO of KBMax
Contact
Contact me about software-related topics via Email, 𝕏, GitHub, or Telegram. For encrypted email, you can use my PGP key. For Signal, email me and ask.