An organic, irregular blob shape as a decorative background element behind a photo, heading, or hero section has become a popular modern design trend, achieved surprisingly simply using eight different border-radius values on a single element.
Click randomize to generate a new organic blob shape using eight independently randomized border-radius corner values, see it rendered live in your chosen color, then copy the CSS needed to recreate the exact same shape.
This technique needs no SVG, image, or JavaScript library — just a single div with a carefully crafted border-radius value using eight numbers (four horizontal and four vertical radii) to create the asymmetric, organic-looking outline.
Because everything runs locally in your browser, results appear instantly and nothing you type or upload is ever sent to a server.
Bookmark this page if you expect to use this tool regularly — it loads fast and behaves the same way every time, with no account needed.
This kind of task shows up constantly in everyday writing, coding, design, and admin work, which is exactly why a dedicated, focused tool saves so much back-and-forth.
A tool that does one job well, without a cluttered interface or unrelated features competing for attention, tends to be faster to use than a heavier all-in-one app.
If you find yourself needing this often, keeping this page open in a tab is usually faster than digging through a bigger software suite's menus.
Because there's no sign-up or installation step, you can jump straight from a search result to a working tool in a couple of seconds.
The interface is intentionally simple, so there's no learning curve — the input goes in, the result comes out, and that's the whole interaction.
Unlike a heavier desktop application, there's nothing to download, update, or configure before you can start using this tool.
Frequently asked questions
Why does border-radius need eight values for this effect?
Each corner of a box can have a different horizontal and vertical radius (defined via a slash-separated shorthand), and varying all eight independently creates the asymmetric, organic curve rather than a simple uniform rounded rectangle.
Can I animate the blob shape to slowly morph over time?
Yes, define two different border-radius states in a CSS @keyframes animation and the shape will smoothly interpolate between them, creating a slow morphing effect.