PenEcho — AI Canvas That Reads Your Handwriting
LinkedIn post by stasbel (Co-founder & CTO @ GetFluently.App, YC W24; ex-Nvidia) — view post
Problem: most AI tools make you type your problem first — fine until it’s an equation, a circuit, or an architecture sketch. You spend longer describing it than solving it.
How PenEcho works
Replaces the chat box with an AI canvas: draw anywhere (handwriting, equations, diagrams) and pause — it reads the marks and their spatial relationships, then writes the answer beside them.
- Canvas: 20,000 × 20,000, but stays light via sparse allocation — only 512×512 tiles where you actually drew; each request sends just that crop plus its position. (Commenters flagged this tile trick as the part others will copy.)
- Answers arrive as drafts you can drag, resize, copy LaTeX from, accept or discard — it never touches your drawing until you say so.
- Runs on an API key, Codex CLI, or Claude Code CLI (CLI mode uses a subscription you already pay for); Kimi K3 / Opus 4.8 / gpt-5.6-terra tested at ~
0.016–0.08 per low-effort request. - Extras: sandboxed HTML widgets on the canvas (live calculators, dashboards, clocks).
- License: AGPL v3, free to self-host. Repo: https://lnkd.in/dkfbG8nj
- Caveat posted by author: handwriting quality depends on the model; Google’s untested — maintainers asking people to report back.
(P.S. section promotes GetFluently.app — noted, not summarized.)