Google developer documentation style guide as Markdown and llms.txt

This repository mirrors the Google developer documentation style guide page for page, as plain Markdown and llms.txt. Every page is reproduced verbatim and resynchronized every week—what you read is what Google wrote.

Hand the guide to a large language model (LLM) and style review stops being guesswork. The model quotes the rule it applies and the page the rule comes from, instead of paraphrasing the guide from training data. The following exchange shows the difference:

You:   The guide says em dashes take spaces around them, right?
Model: No—an em dash takes no space before or after it.
       Source: https://developers.google.com/style/dashes

You can also distill the guide into a reusable technical-writing skill, or read and search it offline, one file per page. The following table shows the three forms the mirror takes:

File	Size	What it is for
llms.txt	4 KB, ~1k tokens	The index: every page as a link, grouped and ordered the way Google's own table of contents groups and orders it. Read this first.
llms-full.txt	515 KB, ~130k tokens	The substance: the whole guide in one file, ready to drop into an LLM's context window or to distill into a skill.
docs/	70 files	One Markdown file per page, verbatim, each recording the URL it came from.

Download the files straight from main, without cloning:

BASE=https://raw.githubusercontent.com/loic-bellinger/google-developer-style-markdown/main
curl -O $BASE/llms.txt
curl -O $BASE/llms-full.txt

This project is not affiliated with, sponsored by, or endorsed by Google.

Distill it into an Agent Skill

llms-full.txt is the file to start from when you write an Agent Skill. It holds the whole guide in reading order, with the source URL of every page, so a distilled SKILL.md can cite the page behind each rule. Spend the 130k tokens once, keep the few thousand you distill, and point the skill back here for the rest.

Open an issue to say how you used it, and link your skill or your repository. If enough people share one, the links move out of this README and into a skills/ directory.

Why you can trust this mirror

Google already publishes every page of the guide as Markdown: append .md.txt to any page URL and the server returns the source. This mirror downloads that source, so nothing is scraped, converted, or reconstructed from HTML.

• Verbatim. Each page is reproduced unchanged: no reflowing, no reformatting, no linting, no stripping of notices. The mirror adds only a front matter block recording the title and source URL of each page.
• A deterministic diff. Two runs against an unchanged guide produce identical bytes. Every diff in this repository is therefore a change Google made, never noise from the mirror, so git log reads as a changelog finer-grained than the guide's own what's-new page.
• Refreshed weekly. GitHub Actions resynchronizes every Monday, only after the test suite passes. The run is all-or-nothing—one failed download and nothing is written—and it stops instead of pushing if it would delete more than a quarter of the pages.

What the mirror doesn't carry

• Images and diagrams. They aren't covered by the content license, and Google's own Markdown carries almost none of them. What survives points at Google.
• The Android and Cloud markers. The guide flags platform-specific terms with CSS-only icons. The icons carry no text, so Google's own Markdown drops them before the mirror ever downloads the page. Check the source page when a term's scope matters.
• Definition lists. Markdown has no syntax for them, so the word list arrives as prose. Cross-references to a term still work: they point at Google, where the anchor exists.
• Some page titles. Of the 70 pages, 19 don't open with a usable heading. The navigation label stands in, recorded in each document's front matter.
• The changelog. The what's-new page dates superseded wording—advice a model shouldn't read alongside the guidance that replaced it—so llms-full.txt leaves that page out. The page is still mirrored in docs/ and still indexed in llms.txt.
• Relative links. Links between pages point at developers.google.com, because that is what Google's Markdown contains.

This is a mirror, not a fork: report problems with the content to Google, not here.

Run the sync yourself

The sync requires uv and Python 3.14.

git clone https://github.com/loic-bellinger/google-developer-style-markdown
cd google-developer-style-markdown
uv sync

uv run gdsm          # refresh docs/, llms.txt, and llms-full.txt
uv run gdsm --help   # options: --output-dir, --concurrency, --timeout

A failed run leaves the mirror untouched, so you can always run it again.

License and attribution

Two different things live in this repository, under two different terms.

The code—everything under src/ and tests/, and the configuration—is released under the MIT License.

The mirrored guide—everything under docs/, and llms-full.txt—is Google's, not this project's, and is not MIT. Per the Google Developers Site Policies, the content of those pages is licensed under CC BY 4.0 and the code samples under Apache 2.0. Google's trademarks and brand features are not included in that license.

Every mirrored document records the URL it was reproduced from in its front matter, and llms.txt and llms-full.txt carry the attribution notice Google asks for. If you reuse this content, keep the attribution and the links back to the source pages.

This project is not affiliated with, sponsored by, or endorsed by Google. "Google" is a trademark of Google LLC.

Contributing

For the two-command setup and the internals—how the sync works, the architecture, what the mirror changes about Google's Markdown (almost nothing), and the design decisions behind its limits—see CONTRIBUTING.md.