Free batch image compressor — local, safe, no upload
Each format gets what actually works on it: one quality slider for JPEG / WebP / AVIF, lossless optimisation for PNG (not a pixel changes, typically 10–25% smaller). Run the batch once and download everything as a ZIP; for a hard size cap (200KB, say) use “batch compress images to a target size”.
JPEG / WebP / AVIF quality
Tune the visual quality of lossy formats before export.
PNG optimisation
PNG is optimised losslessly: higher levels mean smaller files and slower runs.
When you need smaller images
Oversized images show up as slow first paint, upload forms that reject your file, and mail that bounces. One pass usually cuts the size by more than half with no visible difference.
- Faster pages → get hero images down to around 100KB
- A form that only accepts 200KB / 1MB → use “batch compress images to a target size” and enter the limit
- Email or chat → run the batch once before sending
- Archiving → keep the originals, share a compressed copy
What quality should I pick?
Quality is the one knob that trades size for sharpness, and it applies to the whole batch. These are the usual starting points — run once, then drag the Preview divider to check.
- 80%: the everyday pick for photos — no visible difference, files more than twice as small
- 85–90%: for images you will edit again or keep long term — leaves some headroom
- 60–70%: thumbnails and listing images, where “readable” is enough
- Not sure? Run the batch at 80%, see how much smaller it got, then decide whether to go lower
Starting points by use case
These are the settings we reach for first — picked with the file format in mind.
- Product photos: 80% — listing pages load noticeably faster
- Blog and landing-page heroes: 80%; anything wider than 1600px should be resized first
- Email and chat: 85% is plenty; if the size is capped, switch to “batch compress images to a target size”
- Screenshots and UI shots: PNG is optimised losslessly — not a pixel changes, usually 10–25% smaller; convert to WebP if you need it smaller still
Compression vs format conversion
Both bring the size down, by different routes. Picking the right one saves a second run.
- Compression: the format stays put — lossy formats (JPEG / WebP / AVIF) quantise harder, PNG is re-encoded losslessly; pick it when the format must not change
- Conversion: a different codec (PNG → WebP is the common one) often halves the size outright
- PNG only shrinking 10–25% is expected: it is lossless, so re-encoding is all this page can do — go to “Convert image format” for more
- Need both? Chain Compress and Convert into one pipeline in the workflow editor
Three steps for a whole batch
No sign-up, no queue: three clicks and the batch is done — every one of them inside your own browser.
- Add images: click “Choose images” to multi-select, or drag the whole batch into the workbench. JPEG / PNG / WebP / AVIF all go in
- Set the quality: drag the slider above for lossy formats (80% is a fine start for photos); PNG is optimised losslessly here, so quality does not apply
- Hit Compress, then download files one by one or take everything with “Download ZIP”; use Preview and drag the divider to check the result
What this page does — and what it does not
The boundaries, stated plainly, so you do not have to find them by trial and error.
- Formats: JPEG, PNG, WebP and AVIF go in, and every file keeps its own format on the way out (for iPhone HEIC photos use “Convert image format” and pick JPG)
- The resolution never changes: compression only touches the encoding, not the pixel count
- No quotas: no limit on the number of files or the size of each one, and no watermark — nothing is uploaded, so there is no “free 5MB / 20 images” tier to bump into
- The only ceiling is memory: a few hundred ordinary photos per batch, while multi-megapixel giants are better split up
- Hard limits belong on the other page: if it has to come in under 100KB / 200KB, use “batch compress images to a target size” and enter the cap
FAQ
Are my images uploaded anywhere?
No. Compression runs in your browser on WebAssembly, so the files never leave your device and it works offline. There is also no “we delete them after an hour” promise you have to take on faith. Batch size is limited only by memory — a few hundred ordinary photos are fine.
How do I hit a target size, like under 200KB?
Use the other tool, “batch compress images to a target size”: enter a size ceiling and the engine binary-searches the quality range to fit it while keeping as much quality as it can. That page ignores the quality slider — type a number and run.
Will I see a difference? What quality should I use?
Usually not. At 80–85% photos look the same to the eye while the file gets more than twice as small. For archival copies or images you will edit again, go above 90% or keep the original. Every file is encoded once from the original you picked, so nothing compounds.
Why will my PNG only shrink a little?
PNG is lossless, so the quality slider does nothing for it — but this page still does real work: every PNG is re-encoded row by row (picking the cheapest filter per row, and dropping the alpha channel when nothing is transparent). Not a pixel changes, and the file usually gets 10–25% smaller. Going further needs another codec — use the Convert image format page and pick WebP, often another 30%+ smaller at the same visual quality. If the re-encoded file would come out larger, you get your original back untouched.
How many images at once, and how do I get the results?
A few hundred ordinary photos per batch, limited by memory; multi-megapixel giants are better split up. Afterwards, download files one by one or grab everything with “Download ZIP”, and use Preview to compare before and after with the divider.
Does compressing overwrite my originals?
No. Your original files stay on your own disk — we never touch them. The output is a separate new file. The workspace list clears when you close or reload the page, and nothing is left behind on the web.
Could the compressed file come out larger than the original?
No. Every file is re-encoded from the original you picked, and if the re-encoded version would be bigger you simply get that original back — you never receive a larger “compressed” result.
What if the compressed image looks blurry?
Raise the quality slider (85–90% for photos) and use Preview with the draggable divider to see how big the difference really is — at 80% most photos look identical. If the original itself was soft, compression cannot rescue it: go back to the source and reshoot or re-export it.
Does it work on a phone? Do I need to install or sign up for anything?
It works in any modern mobile browser — no install, no account, no watermark. Phones have less memory than desktops, so keep batches of several hundred for a computer. Add it to your home screen and it keeps working offline too.