CSS Border Radius Generator

Create rounded corners with per-corner control.

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Input
Output
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About css border radius generator

CSS Border Radius Generator loads once and then runs on its own. Close the tab and there is nothing left behind, on the machine or anywhere else.

No server sees this. That is a consequence of how the tool is built rather than a policy someone wrote down, which is the version worth trusting.

You will find it under CSS, alongside 11 other tools for the same sort of job.

Generates shorthand and individual corner properties with vendor prefixes.

How to use it

01
Start it
Every control is on the tool itself. Keyboard shortcuts, where there are any, are listed beside it.
02
Watch it run
It updates in the page as you go. Nothing is sent anywhere, so it keeps working with the network off.
03
Close when done
Nothing is stored between visits. Reloading gives you a clean start rather than picking up where you left off.

Examples

Pill-shaped button
Generate CSS for a fully-rounded pill shape using 50% radius
Input
topLeft: 50
topRight: 50
bottomRight: 50
bottomLeft: 50
unit: %
Output
/* Border Radius */
.rounded {
  -webkit-border-radius: 50%;
  -moz-border-radius: 50%;
  border-radius: 50%;

  /* Individual corners */
  border-top-left-radius: 50%;
  border-top-right-radius: 50%;
  border-bottom-right-radius: 50%;
  border-bottom-left-radius: 50%;
}

Questions

Does CSS Border Radius Generator work offline?+

Yes. It is JavaScript running in this tab, so once the page has loaded it needs nothing further from the network. Put the machine in flight mode and it carries on. Nothing you do here is sent anywhere, because there is nowhere for it to go.

Does it remember anything between visits?+

No. Reload the page and it starts from nothing. There is no account, no saved state and no cookie holding your last session. That is a deliberate trade: it cannot lose your data because it never keeps any.

Is it accurate?+

Timing comes from performance.now(), the high resolution clock the browser provides, rather than from setInterval, which drifts by a few milliseconds every tick and compounds over minutes. What can still shift things is the browser throttling a tab in the background, so leave it visible if the timing matters.

Does it make a sound?+

Where a sound makes sense, it is generated with the Web Audio API rather than loaded as a file, so there is nothing to download and nothing to block. Browsers refuse to start audio until you have interacted with the page, which is why the first press is what switches it on.

Can I use CSS Border Radius Generator on a phone?+

Yes. The controls are sized for touch and the layout collapses to one column on a narrow screen. Bear in mind that a phone locking its screen will suspend the page, and timing stops with it.