Who contributed to FastAPI & Pydantic on May 20, 2026?

2 developers shipped this update, including tiangolo and dependabot[bot].

What were the notable FastAPI & Pydantic updates?

🔧 Migrate docs from MkDocs to Zensical, 🍱 Update sponsors: TalorData image, and Bump pymdown-extensions from 10.16.1 to 10.21.3.

FastAPI & Pydantic

FastAPI and the Pydantic + SQLModel async-Python stack

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FASTAPI DOCS LEAVE MKDOCS BEHIND FOR ZENSICAL

By RepoJournal · Filed 06:04 UTC on May 20, 2026 · About FastAPI & Pydantic

2 people shipped this

tiangolo @tiangolo 2 cited

dependabot[bot] @dependabot[bot] 2 cited

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

→ Review FastAPI docs build if you maintain custom documentation pipelines - Zensical may have different output or configuration fastapi/fastapi [plan]
→ Upgrade Pydantic's pymdown-extensions to 10.21.3 or later to close the directory traversal issue pydantic/pydantic [monitor]
→ Pull the IDNA 3.15 bump and test DNS validation if you handle international domain names pydantic/pydantic [monitor]

References

[1] 🔧 Migrate docs from MkDocs to Zensical ↗ fastapi/fastapi
[2] 🍱 Update sponsors: TalorData image ↗ fastapi/fastapi
[3] Bump pymdown-extensions from 10.16.1 to 10.21.3 ↗ pydantic/pydantic
[4] Bump idna from 3.10 to 3.15 ↗ pydantic/pydantic

Quick answers

What shipped 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. In total, 2 commits and 4 pull requests landed.
Who contributed to FastAPI & Pydantic on May 20, 2026?: 2 developers shipped this update, including tiangolo and dependabot[bot].
What were the notable FastAPI & Pydantic updates?: 🔧 Migrate docs from MkDocs to Zensical, 🍱 Update sponsors: TalorData image, and Bump pymdown-extensions from 10.16.1 to 10.21.3.

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