How we picked these compressors
We favoured tools that are honest about what they do, easy to start using, and well suited to a clear use case. Some of the links below are affiliate links, which means we may earn a small commission at no cost to you — see our affiliate disclosure for details. That never changes our recommendations: the free, privacy-first tools come first because, for most people compressing a handful of images, they are genuinely the best option.
PNGifier Compress PNG — free and private
Our own Compress PNG tool runs entirely in your browser, so your images never leave your device and there is no upload, account, or watermark. It is free, fast for one-off files, and keeps transparency intact.
Pros: completely free, fully private (nothing is uploaded), no sign-up, works offline once loaded. Cons: built for individual files rather than bulk-optimising a whole website, and there is no automation or API. If you only need to shrink a few PNGs, start here — see also how to reduce PNG file size.
TinyPNG — the popular smart-lossy service
TinyPNG is probably the best-known online compressor. Its smart-lossy engine squeezes PNG and JPG files hard while keeping them looking sharp, and the results are consistently good with no settings to fiddle with.
Pros: excellent compression, dead simple, handles both PNG and JPG, offers an API and plugins for paid tiers. Cons: images are uploaded to TinyPNG's servers, the free web tool has file-size and batch limits, and heavier use pushes you onto a paid plan.
Squoosh — open-source and hands-on
Squoosh is a free, open-source compressor from Google that runs in the browser. It supports many formats (PNG, JPG, WebP, AVIF and more) and gives you a live before/after slider so you can dial in exactly the quality you want.
Pros: free and open source, fully in-browser so your images stay private, lots of formats and fine-grained controls. Cons: the manual controls are more than some people need, it works one image at a time, and there is no built-in batch or automation.
ShortPixel — bulk and website optimisation
ShortPixel is built for scale. Through its WordPress plugin, API, or bulk web tool it can optimise thousands of images at once, convert them to modern formats, and keep doing so automatically as you add new media.
Pros: great for whole websites, supports lossy and lossless modes, WebP/AVIF conversion, generous one-off credit options. Cons: images are processed on ShortPixel's servers, ongoing use is credit-based, and it is overkill if you only have a few images to compress.
Optimole & Imagify — automatic site image delivery
Optimole and Imagify both automate image optimisation for live websites. Optimole leans on a CDN to compress, resize, and serve images on the fly, while Imagify optimises your media library in place. Either one takes ongoing image work off your plate.
Pros: set-and-forget automation, responsive resizing and modern-format delivery, strong fit for WordPress sites. Cons: subscription-based and tied to your website's traffic or image count, with more setup than a quick one-off tool. For occasional files they are the wrong tool — reach for an in-browser compressor instead.
Lossy vs lossless compression
Lossless compression rebuilds a file to be smaller without changing a single pixel — perfect when you need an exact copy, such as logos, screenshots, or editing masters. Lossy compression goes further by discarding detail your eye is unlikely to notice, producing dramatically smaller files. Most of the tools above offer both; TinyPNG's smart-lossy approach and Squoosh's quality slider are good examples of lossy done well, while PNGifier and ShortPixel let you stay lossless when fidelity matters.
How to choose the right compressor
Match the tool to the job. If you have a few images and care about privacy, use a free in-browser tool like PNGifier Compress PNG or Squoosh — nothing is uploaded and there is no cost. If you want a polished one-click service, TinyPNG is a safe bet. If you are optimising an entire website or library, ShortPixel, Optimole, or Imagify will save far more time through bulk processing and automation. You can also browse our other image tools to handle conversions alongside compression.
Frequently asked questions
- What is the best free image compressor?
- For one-off PNG work, a free in-browser tool like PNGifier or Squoosh is hard to beat — your images never leave your device and there is nothing to install. For compressing an entire website's media, a service like ShortPixel or Optimole saves more time.
- Is it safe to compress images online?
- It depends on the tool. In-browser compressors such as PNGifier and Squoosh process images locally, so nothing is uploaded. Server-based services like TinyPNG and ShortPixel upload your files to their servers, which is fine for most images but worth considering for sensitive ones.
- Will compressing a PNG reduce its quality?
- Not necessarily. Lossless compression rebuilds the file smaller without changing a single pixel. Lossy compression trades a little detail for a much smaller file — at sensible settings the difference is usually invisible.
- Do I need a paid tool to compress images?
- No. Free tools handle individual images perfectly well. You only need a paid plan when you want to bulk-optimise thousands of images or automate compression across a live website.