Draw a box and it becomes a node. Draw a line and it becomes an arrow. Capture the system in your head with one finger, on the train. Fork into plan A and plan B, compare the diff in color, and adopt the winner. AI can turn text or speech into a diagram, too.
Sketching and PNG export are free. The App Store link will be added at launch.
Diagram tools assume a desk. Ideas arrive on the train and in bed. And when you want to compare plan A with plan B, copies of the file pile up and nobody knows which one is current. BoxLine is the notebook that fixes both.
You jot it down in a notes app and redraw it later. Every experiment becomes another duplicate: "architecture_v3_final_2". What changed? Nobody remembers.
Boxes and lines drawn with a finger become nodes and arrows immediately. "Branch from here" creates plan B, the diff is shown in color, and "Adopt" writes the winner back. Every operation stays in the history.
Draw the participants, then draw a line from one lifeline to another and it becomes a message. Reorder from the list.
Write "User -> Server: order" one line at a time and apply. Power users design fast on the phone. Mix with sketching and AI.
Pick what you are building and a target release date; the app lays out a schedule and walks you to release with "N days to go" and today's task. Includes the App Store submission steps.
Draw a rectangle with one finger and it becomes a box. Draw a line from box to box and it becomes an arrow. No mode switching. Circles, diamonds, cylinders, and clouds are recognized too.
"Branch from here" creates plan A and plan B. Overlay the diff in color, then "Adopt" the plan you chose and it is written back to the original.
Type or say "When a user orders, the server checks stock, then..." and AI lays it out as boxes and lines, added as a new branch. Nothing is overwritten, so it is safe to try.
Scrub the timeline to any past state and branch from there. Free keeps the last 20 operations; Pro goes back to the first stroke.
Diagrams are listed by date with a one-line note. Lock Screen widgets open "Draw" or "Speak to diagram" directly.
Export to PNG, SVG, draw.io, and text (Mermaid). Import draw.io files. PNG export is included in Free.
"Tidy" reads the direction of your arrows and spaces the boxes evenly. Undo if you do not like it. Six templates included.
Stored only in your own iCloud; the developer cannot access it. Even on Free, you can export and import the whole notebook as a file.
The only network traffic is the relay server used by the AI features. Your text is used only for generation and never stored. No login required.
Plans branch like Git branches. In the diff, additions are green, deletions red, changes yellow. Once you decide, the adopted plan updates the original diagram.
Sketch boxes and lines with a finger, or talk to "Diagram from text". They become boxes and arrows.
Tap the branch chip and choose "Branch from here". Change anything in plan B; main stays untouched.
Open "Diff", decide with the colors, and "Adopt" to write it back. Export to draw.io or text when you are done.
Free lets you sketch and export PNGs. Branching, diffs, and adoption are unlocked with Pro.
Pro comes with a 7-day free trial. The subscription is charged to your Apple ID at confirmation and renews automatically unless cancelled at least 24 hours before the end of the period. Manage or cancel it in your App Store account settings.
Terms of Use (Apple standard EULA) Privacy Policy
BoxLine is iPhone only. iPad is not supported.
Strokes that are not recognized stay as freehand ink. Right after recognition you can tap "Undo" to turn the box back into ink. Recognition sensitivity has three levels in Settings.
Through the developer's relay server (Cloudflare Workers) to Anthropic's API, used only to generate the diagram. The relay stores nothing except a random device ID generated by the app and the current month's usage count, which expire automatically.
No. The result is always added as a new branch (only an empty diagram receives it directly in main). You can edit it by hand or delete the branch.
Your diagrams stay on the device and keep working within the Free limits. "Export the whole notebook" is available on Free too, so you can take your data out as a .boxline file at any time.
With Pro iCloud sync, the notebook is simply there on the new phone. Without it, export and import the notebook file. The Pro purchase is restored with "Restore Purchases" in the App Store.
With Pro you can import .drawio and .drawio.svg files. Shapes BoxLine does not have are imported as rectangles. Exported draw.io files open directly in app.diagrams.net.
Sketch and export PNGs for free. Try Pro free for 7 days when you want to branch.
Get it on the App Store