Quick start

1. Open the editor

Go to https://fish-zero.com/MDEditor and you are in. Nothing to install, nothing to sign up for, and you can start typing before you have read any of this.

For the full experience — opening a folder and overwriting files in place — use a Chromium-based browser: Chrome, Edge, Brave, or Arc. Firefox and Safari can edit and preview, but saving falls back to a download.

2. Pick a folder

In the Files sidebar, press 📂 Choose folder and select a folder that contains .md files. The browser will ask you to grant access. After that, every .md in the folder (including subfolders) is listed in the sidebar — one click loads it.

With many files, the search box filters by file name; Ctrl+P expands the sidebar and jumps straight into it.
.. Parent walks one directory up.
You don't have to open a folder at all: drop a single .md file onto the window.

Next time you come back, the sidebar shows 📂 Reopen: your last folder. One click takes you back — but the browser will still ask for permission again. That is the browser's security model, not the editor forgetting.

3. Write, and watch the right-hand side

The left pane is the editor with line numbers, the right is the live preview. The toolbar buttons insert syntax rather than hiding it:

Button	What it inserts
Heading (dropdown)	`#` through `######`
Bold / Italic	`text` / `text`
Underline	`<u>text</u>` (Markdown has no underline syntax)
Strikethrough	`~~text~~`
Divider	`---`
Code block	a fence line before and after (three backticks)
Link (dropdown)	text link, URL link, image
Table	asks how many columns, then writes the header and separator rows

Every code block in the preview gets a Copy button in its top-right corner. Scroll down a little and a Back to top button appears in the bottom-right.

4. Save

Ctrl+S (or Save, the green button in the toolbar) overwrites the file you opened. No trip through the Downloads folder, no manual replace.

Save As lets you choose a new location and name.
Copy MD (floating in the top-right corner of the editor pane) puts the whole source on your clipboard.
If the status bar says Cannot overwrite in place — use Save As, this file came without write
permission (dropped files usually do). Use Save As instead.

5. Shape the view

Toggle sidebar — collapse the file list for a wider editor.
Show / hide editor — preview only, i.e. reading mode.
Side-by-side dual preview — a second preview for another document; see dual preview.
Themes — the three icon buttons in the top-right (moon / sun / leaf): dark, light, warm sepia. Hover for the name.
Language — the globe pill in the top-right corner: Traditional Chinese, English, Japanese.
Fullscreen and Print — printing outputs the preview only, never the toolbar.

Whether the sidebar and editor pane are open, plus your theme and language, are remembered in your browser. Next visit looks the way you left it.

Download this page as .md Open it in the editor and you have a ready-made sample document.

← Back to the manual