Markus Schirp

About

Author of production open source across three ecosystems: 50 Ruby gems with 820M+ combined downloads, 400+ Haskell packages on Hackage, and Rust crates on crates.io. DataMapper and ROM core team alumni.

Two decades building developer tools and production systems under regulatory and market pressure. FinTech, startups through to successful exits, new builds and legacy rescues. Security vulnerabilities in third-party financial infrastructure (Avalara, CircleCI) found and responsibly disclosed during regular client work. Remote-first, primarily with US clients. German expat based in Malta.

Manifesto: Self Inflicted Complexity

Most software complexity is not domain-inherent. It's self-inflicted: needless distribution, trapped in dynamic languages, missing tooling, misdiagnosed root causes. The cost is hidden until it isn't.

Self-inflicted complexity is self-reinforcing. Teams "just add another service, database, or vendor" instead of solving the actual problem.

The Exorcism

Diagnosing these problems, adding mitigations to free up development time, and leading the change to fix root causes. With developers, stakeholders, and boards. Not an armchair general: hands-on work that makes it happen.

Mutant

Mutation testing for Ruby. As AI tools rapidly generate code and tests, Mutant ensures those tests meaningfully validate behavior, boosting developer productivity while maintaining quality.

Included in the Trail of Bits Ruby Security Field Guide. Subject of IEEE-published academic research. Used as a pre-deploy gate at Cognito (acquired by Plaid).

Writing

The Contribution Threshold (February 17, 2026): Every project has a contribution threshold. Below it, contributions hurt the project even if CI is green. The gap is filled by human discipline, the most volatile resource you have.

Pattern Parrots and the Semantic Knot (February 7, 2026): AI code generators are great amplifiers. But amplifiers amplify misalignment too. On mutation testing as the deterministic closed loop.

Open Source

Stratosphere: Type-safe AWS CloudFormation generation. Born in Haskell, ported to Rust.

mrs: Rust monorepo with tooling for PostgreSQL (clients, migrations, ephemeral instances), OCI containers, typed HTTP, Git worktrees, and CI automation.

Unparser: Turn Ruby AST into semantically equivalent Ruby source.

Many more at github.com/mbj.