**Model**: Claude Opus 4.6

# Slabo 13px — Upstream Source Investigation

## Summary

Slabo 13px is a size-specific slab-serif typeface optimized for 13px on-screen rendering, designed by John Hudson at Tiro Typeworks Ltd (www.tiro.com) and released in 2013. It was added to Google Fonts on 2014-05-30.

## Designer

John Hudson — Tiro Typeworks Ltd (tiro.com)

## Repository Search

A search for canonical upstream repositories was conducted on GitHub. The following repository was found:

- **TiroTypeworks/Slabo** (https://github.com/TiroTypeworks/Slabo) — repository owned by Tiro Typeworks, described as "Size-specific fonts for online advertising and other web use." The repository contained:
  - `UFOs/Slabo 13px b004.ufo` — UFO source for the 13px variant
  - `UFOs/Slabo 27px b002.ufo` — UFO source for the 27px variant
  - `UFOs/Slabo Xpx b005.ufo` — UFO source for a generic size variant
  - `FontLab Sources/` — FontLab source files
  - `VOLT Sources/` — VOLT OpenType feature sources
  - `TTFs/` — compiled fonts
  - `FEAs/` — OpenType feature files

The repository was confirmed as non-archived with an active `master` branch.

## Commit

Latest commit: `21420697b49ec12ab3fd182a71ffe7c9d804f156` — "Merge pull request #8 from moyogo/moyogo/readme — README.txt: UTF-8 without BOM instead of UTF-16LE"

This commit was verified via the GitHub API.

## Status

Source block was added pointing to `TiroTypeworks/Slabo` at commit `21420697b49ec12ab3fd182a71ffe7c9d804f156` on the `master` branch. This same repository also serves as the upstream for Slabo 27px.

## Confidence

High — The repository is owned by Tiro Typeworks (the font's creator), contains UFO source files for both the 13px and 27px variants, and matches the font metadata.
