Paint that only moves where the paper is wet
A watercolor sim in the browser, with color stored as a spectrum, an SVG you can trace, and no install.
- Category
- Design
- Who it is for
- Someone who wants a wash on a page they already have open, without an install.
- Possible model
- Open source
- Difficulty
- Hard
- Inspired by
- Watercolor Playground · Watercolor Playground
- Original launch
- Watch the launch · Oct 6, 2026
Difficulty is an editorial estimate of technical and operational complexity, not a score.
Startup idea analysis by Startup Ideas. Last reviewed Oct 7, 2026. How we read a launch.
The startup idea
Maks Surguy posted that he open-sourced a watercolor app for the browser. The repo is github.com/msurguy/watercolor-playground. The readme says paint flows only where the paper is wet, colors mix the way pigments do, and washes dry with blooms and tide lines. Color is stored as a spectrum, not RGB, so yellow and blue make green. It says nothing to install, and it works with a mouse, a touchscreen, or a stylus. The post says it can trace an SVG with a brush, write in single-stroke fonts, and flood-fill with a wash. The readme's license is MIT. Bundled fonts keep their own licenses. This page did not paint in it.
The opportunity is the wet paper and the mix, not another drawing app with a watercolor brush tip. A smaller product is a few pigments, a wash that dries, and one SVG you can trace, in the browser. If the mix is still RGB, do not use his sentence.
Do not invent a price. MIT and no install is the offer. Do not say the fonts are his. The readme says they keep their own licenses. Do not treat a painting in the film as a sale.
The problem
Digital paint mixes like RGB. Real watercolor does not, and the good tools ask for an app.
Who would pay for this?
- Primary
- Someone who wants a wash on a page they already have open, without an install.
- Secondary
- A person with a stylus who cares that yellow and blue make green.
- Early adopter
- One brush, wet paper, one traced SVG.
How could it make money?
Possible models. Nothing here is a claim about what Watercolor Playground charges.
- No price. The post and the readme do not sell a plan.
- MIT is the app. The fonts are separate licenses. Say that if you ship them.
- A paid brush pack would be a different product.
What would the MVP look like?
- The browser.
- Wet paper and a dry tide line.
- A few pigments stored as spectra.
- One SVG trace.
- MIT on the repo.
How to validate the idea
- Ask five people who paint if the mix looks like pigment or like a filter.
- If they need an account before the first stroke, you added the part he left out.
- Do not add a gallery until one person finishes a wash they keep.
How to differentiate
- Spectrum, not RGB.
- Paint only on wet paper.
- Nothing to install.
- Do not become a social art network. The wash is the product.
Why this could be interesting now
The post puts a pigment sim in the browser, MIT, with no install. The opening is the wet paper and an honest mix.
Original product launch
This launch is inspiration and evidence that someone shipped, not a partnership. The idea above is our reading of the broader opportunity. Watercolor Playground did not write it.
- Product
- Watercolor Playground
- Source
- Watercolor Playground
- Film
- Watercolor Playground, paint in the browser
- Posted
- Oct 6, 2026 · 0:45
Product that inspired this idea
Maks Surguy open-sourced a watercolor app in the browser. The readme says paint only flows on wet paper, color is stored as a spectrum rather than RGB, and you can trace an SVG. MIT. Nothing to install.
Posted by @msurguy. Watch the original launch. No separate product site is listed unless the post itself is the source.
- paint
- browser
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