Martin Donath

Martin Donath, known online as squidfunk, is an independent software developer best known for creating Material for MkDocs, the documentation theme behind the docs of FastAPI, uv, AWS, OpenAI and tens of thousands of other projects. He now leads Zensical, a new open-source static site generator built by the team behind Material for MkDocs.

Donath worked for about two decades as a developer and consultant. He started Material for MkDocs in 2015 as a side project: he wanted to document a C library he was releasing and found existing documentation tools dated, so he spent around nine months building a theme for MkDocs, then maintained it on Sundays alongside client work.

The theme became one of the best-known projects in the Python documentation world, with more than 27,000 GitHub stars. To pay for it, Donath ran Insiders, a sponsorware model where GitHub sponsors got early access to new features before they were released to everyone. It grew into one of the largest sponsorware projects on GitHub, and he has said it reached about $200,000 a year in revenue.

When the direction of MkDocs 2.0 threatened to break Material and hundreds of ecosystem plugins, Donath decided to start over. In November 2025 he announced Zensical, a static site generator with a Rust core that can read existing mkdocs.yml files, and the next week made Insiders free for everyone and ended the sponsorware model. Zensical is MIT-licensed. Zensical LLC funds it with Zensical Spark, a membership offering early access and support to organizations, and Zensical Studio, an authoring app, rather than venture capital. He works with Timothée Mazzucotelli, creator of mkdocstrings, and Katharina Linnenkugel, who handles community and customers.

Donath matters because his projects show both sides of open-source funding: a sponsorware model that worked for years, and a deliberate move to an independent, product-funded company once a professional team needed predictable income.