Tommy Flyleaf
TOML editor, one edit deep
Only for Mac
Free
Mac
Open a TOML file as a tree, change one value, and save. Every comment, key and line you did not touch comes back exactly as it was. Nothing leaves your Mac.
Tommy Flyleaf is a structure-aware TOML editor. It opens a file, shows it as a tree beside what a save would write, and edits every value by its kind.
A save keeps every comment, the key order, the whitespace and the quoting of everything you did not edit. A Cargo.toml or a pyproject.toml comes back the way you left it, one value different.
What it does:
• Shows the document as a tree, one renderer per TOML type, with the source beside it and the row you are working in lit up.
• Edits values by kind — all eleven of them, the four datetime shapes told apart — and converts a value to another kind where it reads as the target.
• Adds, renames, converts and removes keys, tables, inline tables and arrays.
• Edits comments wherever TOML allows one: above a key, beside a value, or at the end of the file.
• Undo and redo, one step per row worked in.
• Saves atomically. The new file replaces the old in one step, so an interruption leaves the old file or the new one, never half of each. A read-only file is refused rather than replaced.
TOML 1.1.0. Every valid case of the toml-test conformance corpus round-trips byte for byte.
Tommy Flyleaf makes no network connection of any kind: no account, no update check, no analytics, no telemetry, no crash reporting. It writes no configuration directory, no history and no list of recent files.
Named for a bookbinder's apprentice. The flyleaf is the blank page inside a book's cover, the one place in a bound book meant for someone to write on later. The book is somebody else's; write on the page provided, and leave the rest as it was bound.
Open source, MIT licensed: github.com/excelano/flyleaf
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
Nothing in the editor changes. A tree shown as a read-only document now also drops the bin beside each item of a list, which was the last control on those rows that would have changed the document. Applications which embed the tree to show a description rather than edit one get a pane with nothing on it that writes.
The developer, Excelano LLC, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Excelano LLC
- Size
- 8.4 MB
- Category
- Developer Tools
- Compatibility
Requires macOS 12.0 or later.
- Mac
Requires macOS 12.0 or later.
- Mac
- Languages
- English and German
- Age Rating
4+
- 4+
- Copyright
- © 2026 Excelano LLC