Option A
Markdown files
The ownership gold standard — plain files you control, forever. But raw text is austere: hard to read without yet another renderer, images live by reference, and rich layout simply doesn't fit.
local-first · block-based · plain .html files
A second brain you actually own.
CuO Notes is a block editor that writes every note as a clean, self-contained .html file in a plain folder on your device. As pleasant as Notion. As portable as plain text. As yours as paper.
No account needed · runs in your browser · works offline · nothing uploaded
why CuO exists
Every notes app makes you choose. You shouldn't have to.
For years, a second brain meant picking your compromise: own your files, or enjoy writing in them.
Option B
Notion, Apple Notes & co.
Wonderful to write in. But your second brain lives in someone else's database or ecosystem. Export is an afterthought, lock-in is the business model, and leaving is always expensive.
The overlooked answer
HTML
The most universal document format ever shipped. Every device already has a perfect reader — the browser. It handles rich text, images and tables natively, every AI model speaks it fluently, and it will outlive every app on this page. It just never had a great editor.
CuO Notes is that editor. Blocks in front of you, plain .html files behind you. Delete the app tomorrow — every note still opens.
| Markdown files | Notion | Apple Notes | CuO Notes | |
|---|---|---|---|---|
| You own the files | ✓ | — | — | ✓ |
| Readable without a special app | needs a renderer | — | — | any browser |
| Rich blocks, images & tables | limited | ✓ | ✓ | ✓ |
| Works fully offline | ✓ | partly | ✓ | ✓ |
| Any AI agent can work on it | ✓ | API only | — | it's just files |
| No account required | ✓ | — | Apple ID | ✓ |
| Leave anytime, keep everything | ✓ | via export | via export | files are the format |
No export step can save you if the format was never yours. In CuO there is nothing to export — the file on disk is the note.
see it move
Watch it work.
No video, no screenshots — every demo on this page is drawn live, right here, by the same design system the app ships with.
demo 01 — quick switcher
Everything is one keystroke away.
Press ⌘K anywhere. Type three letters. You're on the page you meant — pages, sections and search live in one calm list that never makes you think about where things are filed.
demo 02 — focus mode
Flip a switch. The room goes quiet.
Focus mode clears the sidebar and the toolbar, narrows the page, and leaves you alone with the words. Everything comes back the moment you ask for it.
demo 03 — the file test
The demo that matters: no app at all.
Drag any note out of your folder and drop it on a browser. It opens — styled, images included — because the note is the file. This is the whole promise, and you can test it on day one.
demo 04 — bring your AI
Every AI already speaks your format.
Your notes aren't trapped behind an app or an API. They're plain files in the web's own language — so any AI agent, from Claude to a local model, can read, edit, tag and reorganize your knowledge base right in the folder. Your second brain gets a staff.
what's inside
A full block editor. A plain folder underneath.
Write in blocks
Headings, lists, to-dos, toggles, quotes, callouts, dividers, code — press / and build the page you mean.
A folder, not a database
Your workspace is a plain folder you pick — local, cloud-synced, even a USB stick. Notes nest as real subfolders.
Self-contained pages
Each note is one clean .html file, styles included, images stored right beside it. Share the file; it just opens.
Images & tables that behave
Paste images with captions, alt text, alignment and sizing. Real tables with header rows. All of it lands in the file.
Find everything
Full-text search, #tags, backlinks between pages, and a ⌘K quick switcher that gets out of the way.
Calm by design
Instant autosave, a focus mode that quiets the room, light and dark themes, adjustable width and type size.
Private by default
An installable app that works fully offline. Notes never touch a server — an optional account syncs preferences, never your writing.
Export that means it
One click turns your workspace into a deployable static site, or a .zip backup. Native Mac & iOS apps are on the way.
And the palette keeps growing — even more block types are on the way, and every one of them saves as the same plain .html.
coming soon
how it works
Three steps, no ceremony.
01
Pick a folder
Open the app and choose any folder on your device. That folder is the workspace — no import, no migration, no account.
~/Notes/
02
Write in blocks
Type like you would anywhere. Press / for headings, to-dos, callouts, images, tables. Everything autosaves as you go.
/ heading · todo · callout · table…
03
Own the result
Every page is already a portable .html file on your disk. Open it in a browser, sync it with any tool, publish it, keep it forever.
Notes/ideas/first-page.htmlpricing
Free to think in. Fair to live in.
A block is a paragraph, a heading, a list item. Limits only ever apply to creating new blocks — reading, editing and deleting are never locked.
Just visiting
$0 no account
- Every feature, no sign-up
- Up to 100 blocks
- Your files stay yours, always
Free account
$0 forever
- Up to 1,000 blocks
- Preferences & favorites synced across devices
- Notes still never leave your device
Unlimited
Unlimited lifetime or subscription
- Unlimited blocks, unlimited pages
- Works offline for a month at a time between check-ins
- For people who live in their notes
Whatever the tier, the promise is identical: your notes are plain files in your folder. Downgrading, cancelling, or walking away never takes a single word from you.
questions
The honest answers.
Where are my notes stored?
In the folder you choose, on your device — as ordinary .html files with images beside them. Nothing is uploaded. The optional account syncs only preferences (theme, favorites), never your writing.
What happens if CuO disappears tomorrow?
Nothing happens to your notes. They're self-contained HTML files — every browser on earth opens them, today and in twenty years. That's the whole point of the format.
Which browsers work best?
Chrome and Edge support the full experience — a real folder of your choosing, via the File System Access API. Safari and Firefox work too, using private in-browser storage with one-click .zip backups. Native macOS and iOS apps are in development.
Does it import or export Markdown?
No — and deliberately. CuO doesn't need an exit format because the working format is already the portable one. If you want to publish, the static-site export turns your whole workspace into a deployable website in one click.
Is there sync between devices?
Your notes are files, so they sync with whatever you already trust — iCloud Drive, Dropbox, Syncthing, a git repo. Point CuO at the synced folder on each machine. Built-in preference sync ships today; richer options are on the roadmap.
Start writing in the next ten seconds.
No sign-up. No download. Pick a folder and write — the files are yours before you've typed a word.
Open CuO Notes