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, no activity logging, no AI training on lesson content. Boards live on Cloudflare's edge, are reachable only by URL, and self-purge after 30 days of inactivity. Full privacy stance.