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FASTAPI DOCS LEAVE MKDOCS BEHIND FOR ZENSICAL
By RepoJournal ยท Filed ยท About FastAPI & Pydantic
FastAPI just migrated its entire documentation stack from MkDocs to Zensical, completing a GPU-assisted rewrite that took 5-6 hours of work and signals a shift toward newer documentation tooling.
The FastAPI team shipped a major docs infrastructure change [1], moving away from MkDocs to Zensical. This wasn't a manual port: most of the work was done with Codex on GPT 5.5, using a detailed goal specification and some follow-up tweaking. It's a pragmatic move that shows how the project is evaluating modern tooling for the docs layer. On the sponsorship front, FastAPI updated the TalorData logo in their sponsors section [2], keeping the funding page current. Over on the Pydantic side, maintainers bumped pymdown-extensions from 10.16.1 to 10.21.3 [3], which includes a critical fix for a directory traversal vulnerability in snippet loading when restrict_base_path is enabled. The IDNA library also got upgraded from 3.10 to 3.15 [4], tightening DNS-length validation early in label checking to prevent oversized input from triggering unnecessary contextual-rule processing. These dependency updates are routine but matter for security and spec compliance.
Action items
- โ Review FastAPI docs build if you maintain custom documentation pipelines - Zensical may have different output or configuration fastapi/fastapi [plan]
- โ Upgrade Pydantic's pymdown-extensions to 10.21.3 or later to close the directory traversal issue pydantic/pydantic [monitor]
- โ Pull the IDNA 3.15 bump and test DNS validation if you handle international domain names pydantic/pydantic [monitor]
References
- [1] ๐ง Migrate docs from MkDocs to Zensical โ fastapi/fastapi
- [2] ๐ฑ Update sponsors: TalorData image โ fastapi/fastapi
- [3] Bump pymdown-extensions from 10.16.1 to 10.21.3 โ pydantic/pydantic
- [4] Bump idna from 3.10 to 3.15 โ pydantic/pydantic
FAQ
- What changed in FastAPI & Pydantic on May 20, 2026?
- FastAPI just migrated its entire documentation stack from MkDocs to Zensical, completing a GPU-assisted rewrite that took 5-6 hours of work and signals a shift toward newer documentation tooling.
- What should FastAPI & Pydantic teams do about it?
- Review FastAPI docs build if you maintain custom documentation pipelines - Zensical may have different output or configuration โข Upgrade Pydantic's pymdown-extensions to 10.21.3 or later to close the directory traversal issue โข Pull the IDNA 3.15 bump and test DNS validation if you handle international domain names
- Which FastAPI & Pydantic repositories shipped on May 20, 2026?
- fastapi/fastapi, pydantic/pydantic