Choosing an image format is a trade between three things: how small the file gets, whether transparency survives, and how much detail is thrown away for good. JPEG discards data to shrink photographs and cannot get it back, so every re-save costs a little more. PNG keeps every pixel and every transparent edge, at the price of size. WebP does both jobs and is smaller than either, but older software still stumbles on it. Quality is the same trade made by degrees rather than in one step, which is why a slider can shrink a photograph and do nothing at all for flat artwork. Every tool here says what the change costs — in bytes, and in what it takes away — before you commit to it.
Tools in this category
Pixel Circle Generator
Type a diameter and get a circle drawn on a square grid, with the block count. Thin outline, thick outline with no diagonal gaps, or filled.
Favicon Generator
Turn one image into the whole favicon set — ICO, PNGs, web manifest and the markup to paste. Crop and position the image first, and nothing leaves your browser.
Compress Images Without Uploading Them
Shrink JPEG, PNG and WebP with a quality slider and an optional resize. Sizes before and after, side by side. The files never leave your device.
Open Graph Image Generator
Make the 1200 by 630 card that shows when your link is shared, and copy the meta tags that point at it. Drawn in your browser.
Text Favicon Generator
Make a favicon from a letter or initials — choose the font, colours and shape, and take away the whole set with the markup to paste. No image needed.
Emoji Favicon Generator
Pick an emoji and take away a complete favicon set — ICO, PNGs, manifest and markup. Browse the symbols instead of hunting for the keyboard shortcut.
Suggest a tool
Tell us what is missing and where its numbers should come from.
What should it convert, calculate or generate, and where would the authoritative numbers come from? A link to the standard or publication that defines them is the most useful thing you can send.
Opens your mail app with this page already filled in.
How these tools are built
Every tool in this category runs entirely in your browser: there is no upload, no account and no request to a server once the page has loaded. The numbers behind them are transcribed from the organisation that defines them — NIST for units, the W3C for web formats, the WHO for health measures — and each page names its source next to the formula. A tool whose reference values stop reproducing fails the build and does not ship, which is the whole reason the catalogue grows slowly.