A free online whiteboard for tutoring and teaching
No accounts for students. Open a URL, share it in the video call, draw on the same canvas together. Works on iPad with a Pencil, on Android tablets, and on phones one-handed.
Zero friction for students. No signup, no account, no email. You send the URL, they're in. Especially valuable for tutoring under-13 students whose schools restrict third-party signups.
Real-time math working. Both of you write on the same canvas. Latency is ~100 ms — the student sees your stroke as you draw it.
Handwriting + iPad Pencil. Vector strokes, anti-aliased, crisp at every zoom level. Perfect for language drills, calligraphy, kanji practice.
Paste anything. Drop a photo of a textbook page, a diagram from Google, a URL. Annotate on top.
Save the lesson. One-click PDF export with the share URL embedded as a watermark.
30-day retention. The board sticks around as long as you keep visiting it — auto-purged after 30 days of inactivity for privacy.
How to run an online lesson with cnvs.app
Open a new board. Visit cnvs.app — a fresh URL is generated instantly.
Share the URL. Paste it in your Zoom / Meet / Teams chat. The student clicks and joins.
Teach together. Both of you draw, type, paste images. You can also use Mermaid for quick diagrams: type ` ```mermaid ` in a text node and watch a flowchart render live.
Export when done. Click Print / Download to save a PDF, or just leave the board — the student can re-open it later (cached offline if they installed cnvs.app as a PWA).
Common lesson patterns
Maths workings
Write equations by hand, drag intermediate steps around, undo mistakes (Ctrl+Z), erase. Toggle dark mode for evening lessons.
Language drills
Drop a worksheet image, draw arrows to vocabulary, type translations in colour. Use the eraser to wipe and reuse.
Diagram-heavy subjects
Biology, electronics, programming — paste a reference diagram, annotate. For flowcharts and sequence diagrams use Mermaid in a text node for clean rendering.
Kids on tablets
Two-finger pan, pinch to zoom, tap to drop text. The "?" button surfaces touch tips. Long-press a drawing to drag it.
Privacy
No accounts and no AI training or analytics on lesson content. Limited product analytics covers aggregate page and coarse feature usage without board IDs or access keys. Boards live on Cloudflare's edge, are reachable only by URL, and self-purge from the live service after 30 days of inactivity. Full privacy stance.