What local-first means for a markdown editor
Most note apps put your writing on someone else's computer and give you a window onto it. Local-first inverts that: the copy on your machine is the real one, and nothing has to leave it.
The phrase gets used loosely, so it is worth being concrete. A local-first markdown editor means all four of these hold:
- No account. You open it and start writing. There is nobody to be.
- No upload. Your text is never transmitted to a server, because there is no server that wants it.
- No network dependency. It keeps working on a plane, on hotel wifi, or when the vendor's status page is red.
-
Plain files. Your documents are
.mdfiles you can open in any other tool, not rows in a database you can only reach through an export button.
A browser-based editor can satisfy every one of those. "In the browser" and "in the cloud" stopped being the same thing some years ago.
How a browser can hold your files
Two capabilities do the work, and they behave differently enough to matter:
The File System Access API
Lets a page read and write real files on your disk, with your permission, through the normal
operating system file picker. You open notes.md from your own folder, edit it,
press save, and the bytes on disk change. The file was never copied anywhere. This is
available in Chrome, Edge, and other Chromium browsers.
IndexedDB
A database built into every browser, scoped to a single origin. Documents live on your machine, and no other site can read them. In Firefox and Safari, where the File System Access API is not available, this is what keeps your work between sessions — with the trade-off that you get the content back by downloading it rather than by saving in place.
Browser storage is durable, not permanent. Clearing site data, private browsing, or an aggressive storage eviction can remove IndexedDB content. Treat it as a working copy. Anything you would be upset to lose belongs in a real file, and ideally in version control.
Why anyone should care
The arguments are practical rather than ideological.
Confidentiality by construction. Plenty of writing cannot go into a third-party service: an incident postmortem naming customers, a contract draft, an unfiled patent, medical or legal notes, an internal design document. A tool that never transmits text does not need a privacy policy you have to trust — there is no transmission to audit.
Speed with no asterisk. No sync round-trip means no spinner between keystroke and character. Latency is your display's refresh rate, not your connection's.
No lock-in. When the file on disk is the source of truth, switching editors costs nothing. You are not migrating; you are opening the same files with something else.
It cannot be discontinued out from under you. A cloud note app that shuts down takes your workflow with it and gives you a zip file. A local-first tool that stops being maintained leaves you with exactly what you had: your files, in a documented format.
The honest trade-offs
Local-first is a real position with real costs, and it is not right for every use.
| You give up | What that means day to day |
|---|---|
| Automatic cross-device sync | Your notes are on the machine you wrote them on. Use a folder that already syncs, or version control. |
| Real-time collaboration | No shared cursors or simultaneous editing. Collaboration happens over the file. |
| Server-side backup | Nobody is keeping a copy for you. Backups are yours to arrange. |
| Search across everything | Search covers the open document, not an indexed archive of years of notes. |
If your writing is a shared team wiki with a dozen simultaneous editors, a cloud tool is simply the better fit. If it is drafts, documentation, technical notes, and things you would rather not hand to a vendor, the trade goes the other way.
Offline as a consequence, not a feature
An editor that already works without a server can be installed as a progressive web app and launched from your dock or start menu like any native program. There is no offline mode to switch into, because there was never an online mode it depended on.
Trying it
MarkNow is built this way: no account, no upload, no server holding your text. It offers rich, raw, and dual editing over the same document, renders Mermaid diagrams and KaTeX math inline, and installs as an offline app. Because there is no signup, the cost of finding out whether it suits you is one click.