We build one of these, so a ranked list from us would not be worth reading. Here are the categories, what each is genuinely good at, and the questions that decide between them.
This site is a browser-based, client-side compressor. That means we sit inside one of the categories below and compete with several of the others, so a ranked list of named products written by us would be marketing wearing a lab coat.
What follows instead is the criteria — including the ones where our own category loses. If you want a leaderboard, get it from somebody with nothing in the race.
Does your file leave your device?
For a holiday photograph, this barely matters. For a passport scan, a signature, a medical document, an unreleased product shot or anything covered by a client agreement, it decides the matter on its own — and those are exactly the files people compress, because they are the ones with upload limits attached.
You can test any tool in about thirty seconds: load the page, disconnect from the internet, and try to compress an image. Client-side tools keep working. Server-side tools fail. You can also watch your browser's Network tab for a large upload request while it runs.
Run that test on us too. It is the point of the exercise.
Use a client-side browser tool for occasional work and anything sensitive. Use the command line or a build plugin the moment it becomes repetitive. Use a hosted service when the catalogue is large enough that neither of those scales.
Those three cover almost every real situation, and two of them are free.
Everything below runs in your browser, so you can test any of this on your own files without uploading them.
Shrink JPG and JPEG photographs with a quality slider or an exact target size.
Open the toolOne setting across a whole folder, processed in parallel, downloaded as a ZIP.
Open the toolQuestions
Every answer below is present in the page source, expanded, so it can be read without opening anything.
There is no single answer, and we are not a neutral party — this site is one of them. The right choice depends on whether your files are sensitive, whether the work is repetitive, and what formats you need. The criteria on this page are more useful than any ranking.
For ordinary work, generally yes. Paid desktop software earns its cost through workflow integration, precise control and handling formats browsers cannot open — not usually through producing dramatically smaller files.
Load the page, disconnect from the internet, and try to compress an image. If it still works, the processing is happening on your device. You can also watch the Network tab in your browser's developer tools for a large upload while it runs.
When they come with a large percentage on photographic content, yes. Genuine lossless compression cannot achieve 70–80% on a photograph. What is usually happening is palette quantisation — a lossy step — followed by a lossless save.
If you compress images daily, a desktop application or a scripted pipeline pays for itself in time. If it is occasional, free tools are entirely sufficient and there is nothing meaningful being withheld.
At the top end, command-line encoders — MozJPEG for JPEG, libavif for AVIF, oxipng for PNG. They are free, they beat browser-based tools by a few per cent, and they require comfort with a terminal.
From the blog
Longer, more practical guides from the blog.
Resize before you compress. Measured on one photograph: half the width at quality 80 produced a 16.4 KB file, while full width at quality 40 produced 20.6 KB and looked far worse. The order of operations matters more than the settings.
8 min read
Quality 80 is not 80% of anything. It is an index into a quantisation table. Measured on one photograph: dropping from 100 to 90 removes 77% of the file and 4.2 dB of fidelity; dropping from 40 to 30 removes 17% and costs almost as much.
8 min read
A photograph from a phone can carry the coordinates of the place it was taken, the camera serial number and the exact timestamp. Removing that data is straightforward. Removing it carelessly rotates your photos sideways.
9 min read