CLAUDE.md is the file Claude Code reads before it touches your project: coding standards, architecture notes, the commands you would otherwise repeat in every prompt. It is Markdown, it grows to hundreds of lines, and most people maintain it in the same plain-text pane they use for source code. PenPage gives it a real editor — visual Markdown, editable tables, and a direct link to the actual file on disk.
When Claude Code starts working in a repository, it reads CLAUDE.md from the
project root and treats it as standing context for the whole session. Anything in that file
applies to every request you make, so it is where project knowledge goes to stop being
re-typed: the stack, the commands, the conventions, the traps someone already fell into.
The file is plain Markdown — headings, tables, fenced code blocks, links. Claude Code also
picks up CLAUDE.md files placed in subdirectories, which apply to work inside
those directories, and a personal one at ~/.claude/CLAUDE.md that follows you
across every project on that machine. The same editing problem applies to
AGENTS.md and the other agent instruction files that have converged on the
same shape.
A CLAUDE.md that is actually pulling its weight usually contains:
Stack tables and file maps are the highest-value rows in a CLAUDE.md and the most miserable Markdown to maintain by hand. Adding one column means re-aligning every pipe, and a misaligned table silently stops being a table. In PenPage you edit cells directly, tab between them, insert rows, and the file is written back as clean pipe-table Markdown.
A 300-line CLAUDE.md read in a monospace column all looks equally important. Read the same file with real heading hierarchy, proportional text and rendered tables and the problems surface immediately: two sections saying contradictory things, a command that has not been true since the Docker migration, four bullets that should be one.
If you run Claude Code on a laptop and a desktop, your personal
~/.claude/CLAUDE.md is not in any repository and gets out of sync quietly.
PenPage's optional Google Drive sync keeps one copy current on both, using your own Drive —
nothing passes through our servers.
Copy-paste round trips are how instruction files rot. PenPage can link a folder on your
computer: you grant access to a directory once, and every .md file in it and
its subdirectories becomes editable in place. Save in PenPage and the bytes land in the
actual file — no export step, no second copy to reconcile.
Folder linking uses the File System Access API, which today means a Chromium-based desktop browser — Chrome, Edge, Brave or Arc. On Safari, Firefox or mobile, import and export Markdown files instead, or keep the file in sync through Google Drive.
Keep your global ~/.claude/CLAUDE.md in a PenPage folder with Drive sync on.
Edit it on either machine, and the other one has it next time you open PenPage. Link the
folder on each machine and the file on disk stays current too.
Files that started at 40 lines reach 400 by accretion. Pull the file into PenPage, read it as a document, cut the sections that duplicate what the code already says, and push the result back in one edit — with the repo copy in git, so the diff is reviewable.
For a shared project, the CLAUDE.md is a team artifact and deserves the same care as a README. Draft it locally, get the tables and command blocks right, then paste one clean version into the pull request instead of six commits of formatting fixes.
| Your IDE | GitHub web editor | A notes app | PenPage | |
|---|---|---|---|---|
| Formatted while you type | Split preview | No | Yes | Yes |
| Tables without aligning pipes | No | No | Yes | Yes |
| Writes back to the real file | Yes | Commits directly | No — copy & paste | Yes, on Chromium desktop |
| Works offline | Yes | No | Partly | Yes, installable PWA |
| Across your own machines | Via git | Via git | Their servers | Your Google Drive, or git |
| Content stored on a vendor server | No | Your repo | Yes | No, local by default |
| Account required | No | Yes | Yes | No |
None of this makes the other tools wrong. Fixing one line mid-session is faster in the editor you already have open, and for anything a team shares, git stays the source of truth. PenPage earns its place when the file is long, table-heavy, or you maintain it on more than one machine.
CLAUDE.md. Otherwise import the file.It writes standard Markdown — ATX headings, pipe tables, fenced code blocks. Your content and section order are preserved, but whitespace and table padding are normalized, so the first save can produce a cosmetic diff. Keep the file in git and review that diff once; subsequent saves are stable.
Yes. Linking a folder picks up every Markdown file in it and its subdirectories, so AGENTS.md, README.md, docs pages and skill definitions are all editable the same way.
No. PenPage stores notes locally in your browser using IndexedDB, and only the Markdown files you actually open are read. Google Drive sync is optional and writes to your own Drive account.
Chromium-based desktop browsers — Chrome, Edge, Brave, Arc — because the feature uses the File System Access API. On Safari, Firefox and mobile you can still import and export Markdown, or sync through Google Drive.
Yes. PenPage installs as a PWA and the editor works with no network connection. Folder linking is local anyway, so editing a CLAUDE.md offline works exactly as it does online.
No. The editor, local storage, folder linking and Drive sync are all free, and no account is required to start.
No account, no trial, nothing to install. Open the editor and your first CLAUDE.md is one paste away.