3 best online whiteboards and diagram tools for different ways of thinking
Excalidraw, CNVS, and Mermaid Live Editor compared for visual sketching, instant collaboration, and diagrams as code.
An online whiteboard can mean three very different things: a freehand place to think, a link that gets a group drawing immediately, or a text editor that turns structured definitions into maintainable diagrams. Excalidraw, CNVS, and Mermaid Live Editor each lead in one of those modes.
This is a task-based comparison of browser apps currently listed on Whimera. We used official product documentation and public repositories, checked on August 11, 2026. The list is not sponsored, and “best” means best suited to the named workflow—not a universal ranking.
Which one should you open?
| App | Best for | Collaboration model | Main output |
|---|---|---|---|
| Excalidraw | Visual thinking, wireframes, expressive diagrams | Real-time rooms and shareable links | PNG, SVG, clipboard, Excalidraw file |
| CNVS | Starting a shared board with minimal setup | Share the board URL | Live board and PDF |
| Mermaid Live Editor | Versionable diagrams as text | Share encoded diagram links | Mermaid source and SVG |
The quick recommendation is simple: choose Excalidraw when the drawing itself is part of the thinking, CNVS when the priority is getting other people into the same space quickly, and Mermaid Live Editor when the diagram belongs beside code or documentation.
Excalidraw: best all-around visual canvas
Excalidraw’s hand-drawn style lowers the pressure to make an early idea look finished. That is valuable for architecture sketches, user flows, meeting notes, and wireframes: collaborators can focus on relationships before polishing presentation.
The Excalidraw repository documents an infinite canvas, image and shape-library support, labeled arrows, free drawing, dark mode, and export to PNG, SVG, clipboard, or an open .excalidraw JSON file. The hosted app adds real-time collaboration, end-to-end encryption, offline-capable PWA support, local-first browser autosave, and read-only share links.
The core hosted editor can be opened without creating an account. Excalidraw+ is a separate commercial collaboration product, which is why Whimera records the overall pricing model as freemium.
Best use: sketching a system while the shape of the problem is still changing.
CNVS: best zero-setup collaborative whiteboard
CNVS starts with a unique board URL. Send that link and other people can draw and write on the same canvas without setting up accounts, teams, or a workspace. The CNVS about page describes real-time WebSocket sync, touch-first controls, image pasting, Markdown text, smart connectors, live cursors, PDF export, and an optional kanban mode.
The same page says inactive boards are removed after 30 days. That makes CNVS attractive for quick workshops, tutoring, incident huddles, and disposable planning sessions, but less suitable as the only archive for material that must remain available. Export or move important outcomes before the retention window matters.
CNVS also supports live Mermaid definitions inside text nodes and publishes an MCP/REST interface that lets compatible assistants work with the same board. Those are unusual additions for a deliberately small whiteboard.
Best use: getting a group into a board in seconds, especially on mixed desktop and mobile devices.
Mermaid Live Editor: best diagrams as code
Mermaid uses a text definition to generate a diagram. The Mermaid documentation covers flowcharts, sequence diagrams, class diagrams, state diagrams, entity-relationship diagrams, Gantt charts, mind maps, and other formats. The Live Editor adds an immediate preview and share/export workflow.
This approach is less fluid than freehand drawing, but it has a major advantage: the source can be copied into documentation, reviewed like code, and regenerated consistently. It is a natural choice for technical systems, API sequences, database relationships, and project timelines.
The tradeoff is syntax. A diagram can fail to render because of a small textual error, and highly art-directed layouts are harder to control than on a canvas.
Best use: diagrams that should stay close to technical documentation and evolve through text changes.
A practical decision tree
Ask what will happen to the diagram after the meeting:
- If people need to move shapes freely and explore, open Excalidraw.
- If people need to join immediately from a link, open CNVS.
- If the result should live in a README or repository, open Mermaid Live Editor.
- If the group begins freeform but the final result needs to be maintainable, sketch in Excalidraw or CNVS, then translate the stable structure into Mermaid.
Collaboration and privacy caveats
A collaborative link is also an access mechanism. Before putting confidential information on any board, confirm who can open the URL, whether the session supports access controls, how long the content is retained, and which export becomes the official record. Product documentation can change, so check the current terms for sensitive work.
Whimera records these apps as diagramming or collaboration tools based on documented purpose. A listing is not an endorsement of a particular security model. Review the Excalidraw listing, CNVS listing, and Mermaid Live Editor listing for the source and freshness behind each catalog fact.