The Sketch alternative where the design runs.
Sketch defined a decade of interface design on the Mac. Prototyper starts where that model ends: a canvas in any browser, on any machine, where the design is a real, running application your whole team and your agents work on together.
What Sketch does well
Native Mac craft
A fast, focused, genuinely native app. People who love Sketch love how it feels, and they are right to.
Mature vector tooling
Symbols, libraries, and precise vector editing refined over a decade of interface work.
You keep your files
Local documents you own outright, workable offline. A real point of principle, honored consistently.
Where Prototyper is different
The output runs
A Sketch artboard is a picture of a product. A Prototyper screen is the product: real React you can click, type in, test, and ship.
Any browser, any machine
The canvas lives on the web. Designers on Macs, PMs on PCs, and reviewers on anything all work the same surface.
Agents are participants
Claude Code, Codex, and Cursor join the canvas over MCP and build alongside you, instead of exporting assets for someone else to assemble.
Bring your own agent
The AI building runs on the subscription you already pay for. Prototyper is the workspace, not the model.
Side by side
| Prototyper | Sketch | |
|---|---|---|
| Real running output (React) | Yes | No |
| Full editing in the browser, any OS | Yes | No |
| AI agents as first-class workers | Yes | No |
| Bring your own AI subscription | Yes | No |
| Precise vector illustration tooling | No | Yes |
| Native Mac application | No | Yes |
Comparison reflects our understanding as of July 2026; tell us if something is out of date.
A picture of a product, or the product
Sketch produces artboards: precise, considered pictures of software. The craft is real, and for years it was the best way to specify an interface. But a specification still needs builders. Every artboard waits for an engineer to translate it, and every translation drifts a little from what the designer meant. A decade of handoff tooling, inspectors, exporters, spec generators, exists to soften that translation, and all of it manages the gap rather than closing it.
On Prototyper the design and the software are the same object. You sketch or describe a screen, an agent builds it as running React on the canvas, and refinement happens on the real thing. The state you polish is a working state, not a drawing of one, so nothing is lost between approval and reality.
The platform question
Sketch made a principled bet on the Mac, and the app is better for it. The cost is everyone who is not a designer on a Mac. Editing lives in the native app, so PMs on other machines, stakeholders, and engineers interact through a web viewer and handoff tooling rather than the working file.
Prototyper is browser-native. The same multiplayer canvas opens on any modern machine, editing included, and reviewers join as free viewers with a link. Agents get the same door: they connect over MCP from wherever they run, no particular hardware required. When the whole team can stand in front of one live surface, the review cycle stops depending on whose laptop the work sits on.
Where the AI sits
Sketch has largely stayed out of the AI race, which is consistent with its focus on hand craft. If AI is part of how you want to work, that leaves you assembling your own pipeline: generate elsewhere, import, and reconcile by hand.
Prototyper was built agent-first. You bring your own agent over MCP and it works your canvas with a real file system: reading the brief, building screens next to your sketches, and revising when you point at what is wrong. The plan you already pay for does the construction, and no per-generation meter runs on top of it.
The review cycle, end to end
A Sketch review has stages: export or sync the artboards, send the link, collect comments in the web app, translate the decisions back into the document, then hand measurements and assets to engineering through inspector tooling. Each stage is short. Together they put days between "the design changed" and "everyone has seen it working".
On Prototyper the review is the link. Stakeholders open the live canvas as free viewers, click the running screens, and leave stickies on the exact element they mean. Changes appear for everyone the moment the agent makes them, and there is no downstream translation because there is nothing downstream: the reviewed thing is the built thing.
Where each tool earns its seat
For icon work, illustration, and precise vector craft, Sketch remains an excellent instrument, and Prototyper does not compete for that seat. The same goes for teams whose deliverable genuinely is a static design document with local files they control.
The seat we claim is product work: screens, flows, and prototypes meant to become software. There, the gap between an artboard and a running app is measured in engineering weeks, and removing it changes what a design team can promise. The promise is easy to state: the screen the team approved is exactly the screen users get, with nothing translated, rebuilt, or lost on the way.
Moving over, or running both
Keep Sketch for vector craft and brand assets if that is where it serves you; plenty of teams will. Product screens are the work to move. There is no .sketch import, because importing a picture would miss the point: start from a screenshot, a rough redraw, or a sentence, and the agent builds the running version directly.
A practical first step is one active flow. Port your onboarding or checkout into a workspace, let the agent rebuild it as running screens with your tokens, and compare that review cycle against your current one. The difference is the argument. Trying costs little: the canvas is free to start, viewers are free, and the agent runs on the plan you already pay for. Most teams know within a week which screens are never going back.
Frequently asked questions
- Does Prototyper run on Windows and Linux?
- Yes. The canvas is browser-native, so any modern browser on any operating system gets the full editing experience, not a viewer. There is nothing to install.
- Can I import Sketch files?
- No. You start from a sketch, a screenshot, or a description, and an agent builds a running version. What you bring over is the idea, not the artboard.
- Do I need to know how to code?
- No. You direct with sketches, selections, and plain language; the agent writes the code. People who read code can open any file.
- What does the AI cost?
- Prototyper is free to start. The building is done by the agent subscription you already have, Claude Code, Codex, Cursor, or Copilot, connected over MCP. No separate metered bill.
- Is Prototyper a Sketch replacement?
- For product screens and prototypes, yes. For vector illustration and icon craft, Sketch still earns its seat, and many teams keep it for exactly that.
See it against your current tool.
The fastest way to compare is to put an agent on the canvas and watch it build. Free to start, no credit card.