cnvs.app

What cnvs.app is

cnvs.app is a free collaborative whiteboard for people and AI agents, accessed in a browser or as an installable Progressive Web App. Anyone with a board URL can collaborate live without signing up, and edits sync over WebSockets. On the canvas, users can draw freehand, add Markdown text and sticky notes, build diagrams with boxes and connectors, paste images or URLs, and pan and zoom. Mermaid diagrams—including flowcharts, sequence diagrams, ER diagrams, Gantt charts, and mindmaps—render from text in a canvas node. An empty board can be switched to kanban mode, with columns, lanes, and cards that hold descriptions, due dates, priorities, and assignees. MCP-capable clients and REST API clients can read and edit the same live boards without an API key. Boards can be printed or exported as PDFs; board JSON and task CSV export options are also available. The app works on Android, iOS, and the web, and cached boards can be viewed offline in read-only mode. Traffic is TLS-encrypted, and access keys can restrict writing or both reading and writing. The free plan costs nothing, billed forever, and includes unlimited boards and collaborators; boards are removed after 30 days of inactivity.

Who it suits

cnvs.app suits groups that want a shared canvas for sketches, text, diagrams, or kanban tasks, including collaborators who do not want to sign up. It also suits teams using MCP-capable or REST API clients to work with live boards, and people who need a browser-based app on phones or tablets.

Limits

The free plan is billed forever and includes unlimited boards and collaborators, but boards are purged after 30 days of inactivity with no user-facing recycle bin or individual-board recovery. Per board, developer documentation lists limits of 500 text nodes, 50 images totaling up to 10 MB, and 2,000 strokes.

Getting started

1. Open https://cnvs.app/ in a browser
2. Create or open a board and share its URL with collaborators
3. Install the Progressive Web App on a phone or tablet if desired
4. Use an MCP-capable client or REST API client to access live boards without an API key
5. Set an access key to restrict writing or reading and writing

Verdict

Choose cnvs.app if you want a free shared whiteboard that combines diagramming, kanban, guest collaboration, and access for AI or REST API clients. Look elsewhere if your work needs voting or workshop templates, or if boards must remain available beyond the 30-day inactivity retention period.