SpecialistExcels at automatically generating flashcards and practice quizzes from study notes, but lacks freehand drawing features.
Goodnotes records 3,227,341 monthly visits with +10.8% month-over-month growth and Freemium, Free Trial pricing. OpenFlowKit records 1,437 monthly visits with -70.3% growth and Free pricing.

The open-source diagramming studio for builders
| Dimension / Metric | ![]() | ![]() |
|---|---|---|
| Official Domain | goodnotes.com | openflowkit.com |
| Pricing Model | Freemium, Free Trial | Free |
| Monthly Visits | 3.23M (3,227,341) | 1.44K (1,437) |
| MoM Traffic Delta |
| +314.75K (+10.8%) |
| -3.41K (-70.3%) |
| Primary Market & Share | 🇺🇸 United States (33.8%) | 🇻🇳 Vietnam (92.4%) |
|---|
| Direct Visits / mo | 1.64M | 614 |
|---|
| User Rating | 4.4 | 4.6 |
|---|
| Supported Platforms | Website | Website |
|---|

Handwritten notes, PDF markup, and AI study tools on one canvas
Low-latency ink with palm rejection, cross-out to erase, and handwriting-to-text conversion keeps writing close to pen on paper.
Import contracts, papers, or textbooks and mark them up by hand, with searchable annotations and clean exports.
Search across typed text, handwriting, and sketches, and turn notes into summaries, mind maps, or structured plans.
Work together in shared notebooks, documents, and whiteboards simultaneously, without version conflicts or file ping-pong.

The open-source diagramming studio for builders
Paste a public GitHub repository and OpenFlowKit reads its files in the browser to draw modules and connections, with every arrow cited to the source line it came from.
29 diagram tools for Claude Code, Codex, Cursor, VS Code, Windsurf or any MCP client, so an agent can draw on the diagram you have open, one undo away.
Write or paste Mermaid, D2 or Structurizr; the text and the canvas remain the same diagram, so you can round-trip between syntax and visuals.
Move from system context to containers to components in linked views that all stay grounded in a single architecture model.
SpecialistExcels at automatically generating flashcards and practice quizzes from study notes, but lacks freehand drawing features.

SpecialistTurns course materials into interactive AI study tools, but focuses less on handwritten digital notebooks.
#2
SpecialistStronger online PDF editing and AI chat capabilities, but lacks tablet-optimized handwritten note-taking workflows.
#3SpecialistConverts notes and PDFs into quizzes and flashcards, but lacks stylus-based handwriting and sketching tools.

Provides gorgeous structured block-based document editing, but is built for typed text rather than handwritten notes.
AI diagrams and technical design docs built from your code and systems

AI diagramming, mind mapping and project tools with 50,000+ templates

Organizes notes into interconnected typed objects rather than traditional notebooks, but lacks handwritten ink support.
Free / Open-sourceOpen-source AI automation that unifies agents, flows and 770+ app integrations

SpecialistUses an infinite visual canvas for note organization, but lacks Goodnotes' paper templates and PDF annotation polish.

AI-powered visual collaboration for diagrams, mind maps, and charts

Offers spatial whiteboards for organizing complex research, but lacks Goodnotes' freehand handwriting stylus support.
SpecialistExcels at automatically generating flashcards and practice quizzes from study notes, but lacks freehand drawing features.
SpecialistTurns course materials into interactive AI study tools, but focuses less on handwritten digital notebooks.
SpecialistStronger online PDF editing and AI chat capabilities, but lacks tablet-optimized handwritten note-taking workflows.
SpecialistConverts notes and PDFs into quizzes and flashcards, but lacks stylus-based handwriting and sketching tools.
Provides gorgeous structured block-based document editing, but is built for typed text rather than handwritten notes.
AI diagrams and technical design docs built from your code and systems
AI diagramming, mind mapping and project tools with 50,000+ templates
Organizes notes into interconnected typed objects rather than traditional notebooks, but lacks handwritten ink support.
Free / Open-sourceOpen-source AI automation that unifies agents, flows and 770+ app integrations
SpecialistUses an infinite visual canvas for note organization, but lacks Goodnotes' paper templates and PDF annotation polish.
AI-powered visual collaboration for diagrams, mind maps, and charts
Offers spatial whiteboards for organizing complex research, but lacks Goodnotes' freehand handwriting stylus support.