google/mozc-devices: fifteen April Fools keyboard builds, two of them closed

Two of the fifteen products have no source in the repository

The top-level README lists fifteen products, and each entry ends with a Source line. For the 2010 Drum set version and the 2014 Magic hand version that line reads Not open source. Nothing for those two is in the tree, so anyone arriving for the drum kit or the magic hand will find an announcement link and no files.

The other thirteen point to a folder. Ten live at the top level: mozc-bar, mozc-caps, mozc-conveyorbelt, mozc-dial, mozc-doublesided, mozc-furikku, mozc-mageru, mozc-nazoru, mozc-piropiro and mozc-yunomi. Three sit under third_party instead: mozc-morse for 2012, mozc-flap for the Patapata version in 2013, and mozc-puchi for 2017.

Directory names do not match product names

A folder name will not tell you which keyboard you are reading. The 2013 Patapata version lives in mozc-flap. The 2016 Physical Flick version is mozc-furikku. The 2018 Physical Handwriting version is mozc-nazoru. The 2019 Spoon Bending version is mozc-mageru, and the 2021 yunomi version is mozc-yunomi.

Some names do line up, which makes the mismatches easier to miss. mozc-bar is the 2022 bar version, mozc-caps is the 2023 CAPS version, and mozc-dial is the 2025 Dial version. The reliable way to map a folder to a year is the Source line in the product table, not the directory name.

The table gives the same product in Japanese and English, with the English title written as Google Japanese Input for the early entries and Gboard for the later ones. The project description notes the earlier name, Google Japanese Input / Gboard April Fools.

The release dates move from April 1 to October 1

Every product from 2010 through 2019 carries an April 1 release date, matching the April Fools origin the README mentions. The 2010 entry is Apr 1, 2010 and the 2019 entry is Apr 1, 2019. After that the list jumps to Oct 1, 2021 for yunomi. No product appears for 2020.

From 2021 on, each release date is October 1: Oct 1, 2021, Oct 1, 2022, Oct 1, 2023, Oct 1, 2024, Oct 1, 2025 and Oct 1, 2026. The newest entry, the Conveyor Belt version, has a release date of Oct 1, 2026, the same day as the last push to this repository.

Because each entry is a one-off joke, a reader cannot assume that a folder reflects a shipped product that anyone sells. Each row links an announcement, most also link a promotional video, and none says anything about hardware being offered for purchase.

Spoon Bending splits firmware and 3D model across two folders

The 2019 Spoon Bending version is the only entry that lists two source locations with different jobs. The folder /mozc-mageru holds firmware, schematics and PCB layout. The folder /third_party/mozc-mageru holds the 3D model.

A person rebuilding that keyboard therefore has to pull from both paths. Cloning only the top-level folder gives the electronics and none of the physical shape, and the reverse holds for third_party.

The table does not describe how the two halves connect, or what the enclosure is made from. For every other product it names a single folder, so the electronics and the mechanical parts presumably share it, although the top-level text does not confirm what each folder contains. The per-directory README is the place to check.

Build instructions stop at the top-level README

The README opens with one instruction about the code: refer to the README in each directory for more details. There is no bill of materials, no toolchain version, no flashing command and no wiring guide in the text above that line. Whatever a reader needs to compile and flash firmware sits one level down.

Two recent entries link localized files by name: mozc-dial has a README_ja.md, and mozc-conveyorbelt has a README_ja.md too. The English labels for both point to the folder itself. A reader who only reads English will land on a directory, and the Japanese file is the one the table links for the Japanese title.

GitHub lists C++ as the primary language. Which of the products are written in it, and which use another language, is not stated at the top level.

It is not the Mozc input method and offers nothing to install

The name invites confusion with the Mozc Japanese input engine. This repository is described as circuit diagrams and firmware source for Gboard DIY keyboards. Someone looking for a Mozc download for Windows or Linux, an IBus package, or an Android keyboard app will not find one in the listing.

No GitHub releases exist, and the homepage field is empty. The folders are source for physical hardware, so the output of this repository is a printed board and flashed firmware, not an installable package.

The README adds one disclaimer in a single sentence: this is not an officially supported Google product. Combined with the lack of releases, that means no support channel and no prebuilt artifact to fall back on if a build fails.

Apache-2.0 covers the tree, but two products and the third_party folders sit outside it

The license is Apache-2.0, and a LICENSE file and a CONTRIBUTING file sit at the top level. That covers the code in the repository. It does not give you the two closed products, and the Drum set and Magic hand versions stay unavailable whatever the license says.

A .gitmodules file is also present at the top level, so check it before assuming a plain clone pulls everything under third_party. The README does not explain what it references.

The repository is not archived. The last push was on 1 October 2026, the same day as the newest product release listed, which makes the 2026 Conveyor Belt version the freshest material in the tree. Older folders carry no maintenance claim, and each year's entry is a snapshot of one joke, not a library kept up to date.

Editorial conclusion

Read google/mozc-devices if you want to study the hardware behind Google Japan's joke keyboards and you can follow a schematic, firmware and PCB layout without a step-by-step guide. Skip it if you want a working keyboard app, a Mozc download or a tested bill of materials, because the top-level README holds none of those. Before cloning, open the README inside the one product directory you care about, since each one carries its own build notes and two products have no source at all.

Frequently asked questions

Official sources

1. google/mozc-devices on GitHub
2. Issues
3. License: Apache-2.0
4. README