Compress many images at once, free

Picking a quality level for a whole batch

The strength of a bulk compressor is that one quality setting applies to every file, so the output is consistent rather than a guess per image. The skill is choosing a level that suits the whole folder at once.

A quality around 80 is the reliable default. At 80 the typical photo or screenshot looks identical to the original while shrinking substantially, which is why it is the right starting point for almost any mixed batch headed to the web or to email.

Lower the setting, into the 65 to 75 range, when size matters more than perfection, for example a large gallery on a slow connection or a batch that must squeeze under a tight limit. Photos forgive this well; screenshots dense with small text show it first.

Raise the setting, to 88 or higher, when the images must stay pristine, such as portfolio work, product photography where detail sells, or anything bound for print. You give up some of the size saving in exchange for keeping every visible detail intact.

Compressing in place versus switching to WebP

By default the compressor keeps each file in its original format: a JPG comes out as a smaller JPG, a PNG as a smaller PNG. This is the safe choice when the files must stay in the format they arrived in, for instance because a form or a system expects it.

But formats are not equally efficient, and you can often save much more by switching. Turning on the WebP option re-encodes the whole batch to WebP as it compresses, which is typically smaller than JPG at the same quality and keeps transparency that PNG would otherwise carry as a large file.

WebP is read by every current browser, so for anything headed to the web it is usually the better target. The trade is compatibility with older or non-web software, which may not read WebP, so keep the original format when the destination is uncertain.

The decision is about where the files are going. Keep the format when a system demands it; switch to WebP when the destination is a modern website or app and you want the extra size saving without losing transparency.

How PNG and JPG compress differently

JPG is lossy by nature, so compressing a JPG means re-encoding it at a quality level and accepting a tiny, usually invisible, loss in exchange for a much smaller file. This is where the biggest savings come from, because photos hold so much discardable detail.

PNG is lossless, so it cannot throw detail away the way JPG does. Compressing a PNG instead means storing the same exact pixels more efficiently, which helps most for graphics, logos, and screenshots with large flat areas of colour. The savings are real but smaller than JPG's.

This is why a photographic PNG is often the wrong format to begin with, and why switching it to WebP or JPG saves far more than compressing it in place. A flat-colour PNG, on the other hand, is already efficient and is best left as PNG.

A mixed batch handles both automatically. Each file is compressed in the way that suits its format, the JPGs re-encoded at your quality and the PNGs optimised losslessly, so you do not have to sort the folder before you start.

Why compressing in the browser keeps files private

Every image is compressed on your own device. Your browser decodes each file, re-encodes it smaller, and bundles the results into a ZIP, all without sending a single byte to a server. There is nothing to upload and nothing waiting in a remote queue.

That local design is what makes it private. Because no file leaves your machine, none of your images sit on someone else's server, get logged, or risk being cached online. For ID scans, contracts, medical images, private photos, or confidential client work, that difference is the whole point.

It is also what makes it fast for large batches. Rather than the slow round-trip of uploading a folder and downloading it back, the compressor works across your CPU cores on several files at once. A folder of web images is done in seconds.

And it is why there is no account, no watermark, and no per-file fee. The tool uses your resources instead of renting servers, so it can stay free and let you run batch after batch without hitting a quota or a paywall.

The jobs a bulk compressor is built for

Making a website faster is the headline one. A gallery, a blog, or a product catalogue full of heavy images loads slowly and scores poorly on Core Web Vitals. Compressing the whole image set at once cuts page weight across the board, so every page on the site loads quicker.

Fitting a set of photos into an email is the everyday one. A handful of full-resolution photos easily breaks an attachment limit. Compressing the batch brings the whole set comfortably under the cap while keeping the photos looking the same to whoever opens them.

Preparing an export for upload is the practical one. A folder dumped from a camera, a phone, or a design tool is far larger than any portal wants. Compressing it in one pass gets every file into a sensible size range before you upload, with no per-file fiddling.

Clearing space is the quiet one. A drive or a backup full of oversized images can be compressed in bulk to reclaim a real amount of storage, keeping the pictures usable while shedding the bytes you were never getting value from. If a specific KB target is required, the compress-to-size tool takes individual files the rest of the way.