Local processing · Quality comparison supported · Mobile‑compatible
Drag images here, or click to select
Supports PNG / JPEG / WebP / AVIF / GIF / BMP
ExtStore Image Compressor is a free tool that shrinks image file sizes without sending your pictures anywhere. Every file you drop in is decoded, re-encoded and saved by your own browser.
Because the work happens on your machine, there is no upload progress bar, no queue and no file size cap imposed by a server. A folder of 50 photos is processed as fast as your CPU can handle it, and the images never exist anywhere except in the tab you are looking at. That also means the tool keeps working after the page has loaded even if your connection drops.
This matters for anything you would rather not hand to a third party: product photography before launch, screenshots containing internal dashboards, scans of documents, or client work under NDA. The privacy guarantee here is structural rather than a policy promise — there is no server endpoint that could receive your files in the first place.
Drag files straight onto the drop zone, or click it to open the file picker. You can add PNG, JPEG, WebP, AVIF, GIF and BMP files, and you can keep adding more while earlier ones are still being processed.
Leave it on "Original" to keep each image in the format it arrived in, or tick one or more of JPEG, WebP, PNG and AVIF. Selecting several formats encodes every image into each one, which is a quick way to see which format wins for your particular picture.
The quality slider runs from 1 to 100 and defaults to 75, which is a good balance for photographs. Lower values compress harder and introduce more visible artefacts; higher values preserve detail at the cost of file size. For PNG the slider controls palette size instead, and only 100 keeps the output fully lossless.
Each finished image shows its new size and the percentage saved. Open the quality comparison to inspect the compressed version against the original before you commit, then download files individually or grab everything at once as a ZIP.
Compress a whole set of images in one pass, with a worker pool that spreads the work across CPU cores instead of encoding one file at a time.
Encode to JPEG, WebP, AVIF or PNG — or convert between them, such as PNG to WebP or JPEG to AVIF — and compare the results before choosing.
A split view and a draggable slider let you pan and zoom the original against the compressed output, so you can judge artefacts at full pixel scale rather than guessing.
Once loaded, the page needs no network access. The optional Chrome extension makes that permanent and adds the compressor to your browser toolbar.
Export every compressed image in a single archive instead of clicking through a long list of individual downloads.
There is no sign-up, no watermark, no daily quota and no per-file size ceiling beyond what your own device can process.
If you are not sure, keep the original format and lower the quality slider a little — that alone usually removes a surprising amount of weight. When you do want to switch, this is how the four options differ in practice.
Typically 25–35% smaller than a JPEG of comparable quality, supports transparency, and is supported by every current browser. This is the best first choice for images on a website.
Often 50% smaller than JPEG and noticeably better at preserving flat colour and gradients without banding. Encoding takes longer, and very old browsers may need a fallback, so it suits assets you compress once and serve many times.
Universally supported by any piece of software that can open an image, which makes it the right pick for email attachments, older systems and upload forms that reject anything else. It cannot store transparency.
The right format for screenshots, logos, line art and anything with sharp edges or text. Note how quality works here: at 100 the output is truly lossless and every pixel is preserved, while any lower value reduces the colour palette to shrink the file — visible first as banding in gradients. Photographs saved as PNG stay much larger than they need to be, so use WebP or AVIF for those instead.
No. All compression runs inside your browser through WebAssembly, and the site has no upload endpoint. Your files stay on your device from start to finish, which you can verify by watching your browser network tab while compressing.
It is free with no account, no watermark and no daily quota. There is no server-imposed size limit either — the practical ceiling is your device memory, since very large images have to be held in RAM while they are decoded and re-encoded.
It depends on the source. Photos straight from a phone or camera often drop 60–80% at the default quality of 75 with no visible difference. Images that have already been compressed once will shrink far less, and re-compressing them repeatedly degrades quality.
JPEG, WebP and AVIF are always lossy, so some information is discarded — though at quality 75 the difference is usually invisible at normal viewing size. PNG is only lossless at quality 100; below that the palette is reduced to save space. Use the built-in comparison view to check the result before you download.
PNG, JPEG, WebP, AVIF, GIF and BMP can all be read. Output can be JPEG, WebP, AVIF or PNG, so the tool doubles as a converter — for example PNG to WebP, or JPEG to AVIF.
Yes. The interface adapts to small screens and you can pick images from your camera roll. Bear in mind that phones have less memory and slower CPUs, so large batches take longer than on a desktop.
Yes. After the page has loaded, compression needs no network at all and will keep working if you go offline. Installing the Chrome extension gives you a permanently offline version in your toolbar.
No. Re-encoding produces a new file from the decoded pixels, so EXIF data including GPS coordinates, camera model and timestamps is not carried over. For sharing images publicly this is usually a privacy benefit, but keep your originals if you need that information.
Pick JPEG or WebP as the output format, then lower the quality slider and recompress until the size shown falls under your target. WebP usually reaches a given size with fewer visible artefacts than JPEG. If quality alone is not enough, resize the image to smaller dimensions first — halving the width and height cuts the pixel count by 75%, which matters more than any quality setting.
Strictly speaking, re-encoding a JPG always discards some data — but at quality 85–90 the loss is invisible at normal viewing sizes, and phone photos still shrink by half or more. The tool also strips EXIF metadata, which removes a few extra kilobytes for free. If you need a mathematically lossless result, keep the original file; lossy formats cannot be re-saved losslessly.
Compressing keeps the same dimensions but encodes the pixels more efficiently, so the image looks the same size on screen. Resizing reduces the actual pixel dimensions — a 4000px photo shrunk to 1600px is a fraction of the original size even before compression. For the biggest savings, resize first and then compress here.
Convert them to WebP or AVIF at quality 70–80, which typically cuts page weight by half compared with JPEG or PNG without a visible difference. Lighter images improve load time and Core Web Vitals scores such as LCP, which is also a ranking signal for search engines. Batch mode lets you process a whole page's assets in one pass.
Yes. Choose JPEG at quality 70–75 for photos — most drop well under 1MB each, small enough for the 20–25MB attachment limit of Gmail and Outlook even in a batch. Download everything as a ZIP and attach that single file to keep things simple.
If the error mentions insertBefore or removeChild, the cause is almost always browser page translation or a translator extension rewriting the page structure, which conflicts with the app's rendering. Turn translation off for this site: in Chrome or Edge, click the translate icon in the address bar and disable "always translate this site"; if you use a translator extension such as Immersive Translate, add this site to its never-translate list. A built-in Chinese/English version is available from the language switcher in the header, so machine translation is not needed.
This tool collects nothing: no account, no analytics, no advertising, no tracking cookies. Your chosen output format and quality are remembered in your browser’s local storage so the controls look the same next visit, and that preference never leaves your device. The full details are in the privacy policy and terms.
