I Built My Own Diagramming Tool — No Framework, No Runtime, Just Canvas

I Built My Own Diagramming Tool — No Framework, No Runtime, Just Canvas

Terry Davis had a point. Not the most comfortable quote to open with in 2025, but the idea sticks: if you rely on tools without understanding them, you don't really own your work.

I've been using Draw.io and Excalidraw for years. Great tools. But every time I needed to explain an architecture, sketch a flow, or share a quick diagram during a call, I found myself fighting the tool instead of thinking.

So I built Markasso.

The name is straightforward: Marker + Picasso. A whiteboard engine for the browser, built from scratch — no dependencies, no framework, no runtime. Just the canvas API and a keyboard-first philosophy.

Why from scratch?

Because I wanted to understand every line of it. And because "zero dependencies" isn't a performance optimization — it's a design constraint that forces clarity. When you can't reach for a library, you have to think harder. The result is something lighter, faster, and fully yours.

Understanding what you're building doesn't mean doing everything alone. I used Claude as an AI agent throughout the process — for architecture decisions, code review, and working through edge cases. Lorenzo Cataldi (github.com/lc-d) helped with the visual design side. The point isn't to be a lone genius. It's to stay on top of every decision, even the ones you delegate.

What it does:

• Keyboard-first navigation and shortcuts (fully documented)


• Mermaid diagram support out of the box


• Custom export/import format so you can move your work between sessions


• Dark theme by default (20+ years of screens will do that to you)


• No profiling, no tracking — just Cloudflare for analytics and CI/CD

Who is it for?

Developers who need a whiteboard for system design, architecture reviews, or explaining things to a colleague on a call. But also anyone who wants to draw on a dark page without logging in somewhere first.

It's young. It'll break. But it has potential.

markasso.it

Try it, break it, tell me what's wrong. Every report, complaint, or comment is welcome.