Compress, resize and crop images — in your browser

CropShrink is a free image editor that runs entirely on your own device. Open a JPG, PNG, WebP or AVIF, crop what matters, resize it with a real resampling filter and export a smaller WebP, AVIF, JPEG or PNG. No upload, no account, no watermark, no queue.

The editor above is the whole product. Everything below explains how to get the most out of it — which format to pick, what the quality slider is actually doing, and why the resize method matters more than most tools admit.

How to compress an image without losing quality

Most of the size in a photograph is detail your eye never resolves. Compression works by discarding that first, so the whole job is knowing where “invisible” stops. Three steps get you most of the way:

1. Resize before you compress. A 4000 px-wide photo shown in an 800 px column is carrying twenty-five times more pixels than it needs. Halving the dimensions removes about 75% of the pixels — almost always a bigger saving than anything the quality slider can do, and with no visible cost at the size you are actually displaying.
2. Choose WebP unless you have a reason not to. At the same perceived quality WebP is typically 25–35% smaller than JPEG — though only 15–20% when the picture is already a JPEG — and every major browser released since 2020 supports it.
3. Start at quality 80 and work down, not up. Watch the output size and the comparison divider at the same time. Photographs usually hold up to about 70. Flat gradients — skies, studio backdrops, soft shadows — are where artefacts appear first, so keep those above 80. Below 60 you will see banding and blocking on almost anything.

Why your images never leave your device

When you open an image here, the browser reads the file straight from disk into a <canvas>. Resizing runs in a Web Worker on your own CPU, encoding goes through the browser’s own image encoder, and the download button points at an object URL built in memory. At no point is there a request that carries your picture anywhere.

You don’t have to take that on trust. Checking it takes about ten seconds:

1. Open your browser’s developer tools — F12, or ⌥⌘I on a Mac — and select the Network tab.
2. Drag an image into the editor above and change a few settings.
3. Watch the request list. Nothing goes to a server: the only new entries begin with blob: or data:, which is the page moving your image around your browser’s own memory. The privacy policy has a longer version of this check.

Because everything happens inside the tab, closing or refreshing the page discards the image and every edit with it. There is nothing stored, nothing queued, and nothing to ask us to delete later. The privacy policy sets out the full detail, including what the web server itself records.

WebP, AVIF, JPEG or PNG — which should you use?

CropShrink exports four formats, and the choice is almost always settled by two questions: is it a photograph, and does it need transparency?

PNG is lossless, which is why the quality slider switches off when you select it — there is nothing to trade. That makes it right for a screenshot of text or a logo with hard edges, and wrong for a photograph, where it will often produce a file several times larger than the JPEG you started with.

JPEG has no alpha channel, so anything transparent is flattened onto white on export. If your image has a transparent background and you need to keep it, choose WebP, AVIF or PNG.

Converting between them is the same operation as compressing: pick the format and export. PNG to WebP, JPG to AVIF, PNG to AVIF and WebP to AVIF are the most common cases.

AVIF gives the smallest files: at the same quality setting it came out 10–35% smaller than WebP on our sample photo and screenshot. The AVIF quality slider is matched to WebP’s, so switching from WebP to AVIF at 80 keeps the look and shrinks the file; the AVIF vs JPG, AVIF vs WebP and AVIF vs PNG guides compare them in full. The cost is time: no browser can encode AVIF itself yet, so CropShrink runs libavif, compiled to WebAssembly, on your device. It is downloaded from this site the first time you choose AVIF, and each encode takes a second or two for a typical photo rather than a moment. Every current browser opens AVIF; older software, many email clients and some image editors do not.

Lanczos3, Catmull-Rom, Mitchell: why the resize method matters

Resizing sounds like arithmetic, but discarding three quarters of the pixels in a picture means deciding what the survivors should look like. That decision is the resampling filter — and most online tools don’t offer one. They hand the job to the browser’s built-in smoothing, which is fast and soft.

CropShrink runs three proper filters in a Web Worker, with colour premultiplied by alpha so transparent edges don’t pick up dark fringes:

There is more on choosing a filter and a width on the resize page, and a full comparison of the four methods on the same photograph. One caveat that no filter can get around: enlarging an image cannot invent detail that was never captured. If a resized picture looks soft, the usual cause is that it was scaled up rather than down.

Common image sizes for social media and the web

Most “what size should this be” questions have one right answer. If the shape is wrong, crop to the ratio first, then enter the width in the Resize panel and leave Maintain aspect ratio switched on — the height follows.

What CropShrink does, and what it doesn’t

Being straight about the edges of a tool saves you finding them at the wrong moment.

Frequently asked questions