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InkFlow: a local-first infinite canvas with a C++ and WebAssembly engine

InkFlow is an infinite-canvas web app for thinking and organizing tasks that works without sign-up and keeps data in the browser. Drawing runs on a C++ engine compiled to WebAssembly, collaboration happens in real time across devices, and handwriting turns into tasks with in-browser text recognition.

Gomes Code product
Web product · productivity
See it liveSource code

Client and context

Productivity tools tend to become endless lists. InkFlow does the opposite: dump ideas on a free canvas and pull one task at a time into a focus mode with a timer.

The problem

“I want to sketch ideas like on paper, with no account, without my data going to a server, and turn the sketch into a task.”

Constraints

  • Smooth drawing even on tablets, without freezing the page.
  • User data only on the user's device.
  • Cross-device collaboration without a data server of its own.

Decisions and trade-offs

  1. A C++ drawing engine compiled to WebAssembly

    Why: Stroke computation leaves JavaScript and gets close to native performance. The cost is one more build step.

  2. Local-first with IndexedDB (Dexie.js)

    Why: Works offline and without sign-up; users can export everything. No central database to maintain and no personal data in custody.

  3. Peer-to-peer sync with Y.js and WebRTC

    Why: Devices talk directly to each other; only signaling goes through a light worker. No data server.

  4. Text recognition in a Web Worker

    Why: OCR (Tesseract.js) runs in the background, so handwriting becomes a task without freezing the canvas.

What we built

  • Infinite canvas with pen, eraser, shapes, lasso selection and PDF export.
  • Task stack, Pomodoro focus mode, Eisenhower matrix and productivity heatmap.
  • Magic wand: handwriting becomes a task through in-browser OCR.
  • QR-code pairing and real-time collaboration across devices.
  • Light and dark themes, Portuguese and English, installable as an app.
inkflow.danillogomes.com
InkFlow canvas with drawing tools on the left and the task stack on the rightInkFlow canvas with drawing tools on the left and the task stack on the right
Canvas and task stack
inkflow.danillogomes.com
InkFlow home page with a button to try it without sign-upInkFlow home page with a button to try it without sign-up
No sign-up entry
InkFlow canvas on mobileInkFlow canvas on mobile
On mobile

Results

  • 0accounts or data servers needed to start using itSource: Live app behavior
  • 3languages in the codebase: TSX, TypeScript and C++ (drawing engine)Source: InkFlow repository, Oct 13, 2026

This case's tile

Non-blank source lines by language, counted in the repository (src and wasm folders).

InkFlow lines of code by languagelines
TSX (interface)3,555
TypeScript (logic)2,437
C++ (drawing engine)74

Source: InkFlow repository · 2026-10-13

Technologies

  • React
  • TypeScript
  • C++
  • WebAssembly
  • Y.js
  • WebRTC
  • Dexie.js
  • Tesseract.js

See it live: inkflow.danillogomes.com

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