Code editing
Syntax highlighting for more than 30 languages, with line numbers, word wrap and auto-indent. The language is detected from the file name.
Free and open source · macOS
A plain, fast editor for text, Markdown and CSV.
Plainfile is a native Mac app for plain text and source code. Markdown files open as rich text that you can edit directly, and CSV files open as a table. Plainfile always saves your work as plain text, so the files keep working in every other app.
macOS 26 or newer · No account · No tracking
What Plainfile does
Each kind of file opens in the view that suits it, and every document lives as a tab in one window.
Rich Markdown
Markdown opens as formatted text with headings, lists, tables and code blocks. Press Command-Shift-M to see the source.
CSV tables
CSV and tab-delimited files open in a fast table. You can sort, filter, edit cells, and add or remove rows and columns.
Tabs in one window
Every document opens as a native macOS tab. The Window menu can close other tabs, or the tabs to the left or right.
Native documents
Autosave, versions, Open Recent, rename, and Find and Replace all work the way they do in other Mac apps.
Encodings and line endings
Detects UTF-8, UTF-16, Latin-1 and Windows-1252, and keeps the file's LF, CRLF or CR line endings when it saves.
Private by default
The app has no network access, no account and no tracking. It only opens the files you choose, and your files stay on your Mac.
Open source
The full source code is on GitHub under the MIT License. It is written in Swift with SwiftUI and AppKit.
Built in the open. You can read the code, report a problem, or send a pull request on GitHub. Plainfile was written mostly with AI coding agents, and it is shared in case it is useful to other people too.
View on GitHub