DeutschView and edit Markdown files for free.And work on them with your AI agent.
Open individual Markdown files in a focused window and edit them together with your AI agent in real time. You can work side by side, or hand your agent full control.
- Windows, Mac and Linux
- Free and open source
- No account, no telemetry
- Works offline
Collaborate with your agent in the same file and track every change.
Your agent connects to Zettelblock through the command line (zblock) or MCP, and starts it if it isn’t running yet. While it edits the file you have open, you can keep writing, because its changes leave your cursor and your scroll position where they are. If you’d rather watch, give your agent full control, and it opens the file, scrolls to its edit and selects it for you.
Open and show files
Your agent opens, creates and closes files in tabs, and can show each one as Markdown, plain text or a table.
Read and edit
Your agent reads the text as you see it, unsaved changes included, and changes only what it needs to.
Select and scroll
Your agent can read what you selected, select text for you, and scroll to a line or a heading.
Settings and window
Your agent can set the theme, zoom, text width or spell check languages, and with your permission, your shortcuts.
Works with your AI agent of choice
Run zblock connect once, or turn it on in Settings → Agents, and Zettelblock installs a skill for Claude Code, Codex or OpenCode. Chat apps without a terminal can use the optional MCP server, zblock mcp, instead.
Open notes.md in Zettelblock and make the second paragraph shorter.
I'll open it in Zettelblock first, so you can follow along.
zblock open notes.md
zblock read
The second paragraph says the same thing twice. I'll cut it to one sentence.
notes.md1 change
Done. The open tab shows the shorter paragraph, and your cursor is where you left it.
Features
Single files, no setup
Open any .md file from your file manager, with Ctrl+O (Cmd+O on a Mac), by drag and drop, or with zblock open.
Live Markdown formatting
Headings, lists, tables, code, math and callouts show styled while you write, and the Markdown marks appear only where your cursor is.
Keep working where you left off
When you start Zettelblock again, your tabs come back at the same line, with the cursor where you left it. And if you close a tab by mistake, a shortcut opens it again.
Intuitive table editor
Start a table by typing it in Markdown or by pasting cells from a spreadsheet or a web page, then edit and resize the table as you like. The editor is flexible, but what it saves is always a plain Markdown table.
Split the window into panes
Drag a tab to the edge of a pane to split the window, with room for up to three panes across and three down. Keep your notes beside a draft, or watch your agent work in one file while you write in another.
Separate change histories
Changes from your agent, or from any other program, stay out of your own undo history, so the two never get tangled. Undo the agent's newest edit with one command, or pick an earlier round from the history and see exactly which lines it changed.
Auto save and instant refresh
Zettelblock saves 300 ms after you stop typing. When another program changes the file, the tab shows the change at once.
Quiet themes
There are four themes, each in light and dark: Blatt (leaf), Papier (paper), Moos (moss) and Tinte (ink). On top of that, you can choose the colors of links, headings and other parts of the text.
Private and offline
Zettelblock has no telemetry, you need no account, and your files stay on your computer. The app only goes online to load a web image that a file links to, and to look for and download updates, based on your settings.
Get Zettelblock for your computer
Pick the build for your system. Zettelblock runs on Windows, Mac and Linux.
Windows
Installer for 64-bit Windows.
macOS
Disk image for Macs with Apple silicon or Intel.
Linux
Pick the .deb or the .rpm package.
Questions and answers
Which systems does Zettelblock run on?
Zettelblock is available for Windows, Mac and Linux.
Which files does Zettelblock open?
Markdown files (.md and similar endings) open in the live preview. Zettelblock also opens .txt, .log, .json, .yaml, .toml, .ini, .xml, .csv and .tsv files, where JSON, YAML, TOML, INI and XML show with syntax colors and CSV and TSV show as a table. If you want a different view for a tab, choose “View as” in its right-click menu.
How does Zettelblock update?
On the first start, Zettelblock asks you how you want updates: manually, with a notice when there is a new version, or automatically. Until you answer, or until you check by hand, Zettelblock contacts no update server. The Windows version and the macOS app in your Applications folder update themselves. With the .deb or .rpm package, or a macOS app started from the disk image, Zettelblock shows that there is an update and links to the download section.
What does Zettelblock cost?
Nothing. Zettelblock is free for everyone, also in companies and for client work, and it is open source under the MIT License.
Do I need an account?
No. Zettelblock has no account and no sign-in. It simply opens the files on your computer, and it works offline.
Which AI agents work with Zettelblock?
Claude Code, Codex, OpenCode and other agents that can run commands in a terminal all work. zblock connect installs the skill that shows them how. For chat apps without a terminal there is an optional MCP server, zblock mcp. Even agents that change the file on disk with their own tools work, because the open tab updates at once.
Can I limit what my agent can do?
Yes. In Settings → Agent permissions, you turn each agent action on or off. By default, all actions are on, except changing your keyboard shortcuts. When an action is off and an agent tries it, the agent gets an error and tells you where to turn it on. Only you can change the switches. An agent cannot turn one back on. Note: the switches cover what agents do through Zettelblock. An agent with its own file tools can still change files on disk. If the file is open in Zettelblock, you can take that change back with Undo agent change.
Can I undo what my agent changed?
Yes. After a change from outside, a bar at the top of the tab shows who made it: “An agent” or “A program on disk”. Undo agent change takes back the newest change while your own later edits stay, and you can repeat it to go further back. Redo agent change brings a change back. This does not affect your own undo and redo history. If you have edited the agent’s text since, Zettelblock leaves the change in place and opens the History with a note instead.
What does the History of a tab keep?
While Zettelblock is open, the History of a tab keeps the last 20 rounds of changes from outside. A round collects the changes that come less than 5 seconds apart, and for each one you see the time, whether an agent or a program on disk changed the file, and the lines added and removed. Select a round to see the differences and restore the text from before it, which your normal undo can take back. The History lives in memory only, so Zettelblock does not write it to disk or send it anywhere, and it clears when you close the tab or Zettelblock.
Where are my files?
On your computer. Zettelblock opens and saves each file where it is. There is no cloud and no sync.
Are you enjoying Zettelblock? Please support it.
Zettelblock is free and open source. If it helps you, you can say thanks by buying a digital thank-you note.