PDF Slim
Shrink heavy PDFs, with the quality left entirely up to you.
PDF
Compress JPG, PNG and WebP images
Compress, resize, convert, rotate and crop JPG, PNG and WebP files. Up to 20 at a time, 12 MB each.
Compression & size optionsQuality 80
Presets
JPG stays JPG, PNG stays PNG. HEIC comes back as AVIF, which is the closest format that can be written.
Encoder options
JPG
Chroma subsampling
4:2:0 halves the colour detail, which is invisible on photographs but smears coloured text and sharp edges. Use 4:4:4 for screenshots and graphics.
Drop your images hereChoose your images
or pick them from your computer — up to 20 at a time.
JPGPNGWebPAVIFHEICGIFMax 12 MB each
How it works
- Step 1
Drop your images
Drag up to 20 JPG, PNG or WebP files onto the page, or browse for them. Anything too large or the wrong type is refused straight away, with the reason.
- Step 2
Adjust anything you like
Set a quality, a file size to hit, or let Smart mode find the lowest quality that still looks identical. Resize, convert, go lossless, and rotate or crop each picture. Every change is applied straight away without uploading again.
- Step 3
Name them how you like
Keep your original file names, replace them with your own, or use random ones — plus optional prefix, suffix and numbering. A preview shows the result before you download.
- Step 4
Download what you need
Take images one at a time, or grab the whole batch as a single zip. Files are removed from the server an hour later.
What actually happens to your file
Each image is re-encoded at the quality you choose and its metadata is dropped. EXIF orientation is applied to the pixels before anything else, so photos from a phone stay the right way up — and a crop means what it looks like on screen.
- JPG
- mozjpeg tuning, progressive and chroma both selectable
- PNG
- palette with colour and dither control, or fully lossless
- WebP
- effort 6, lossless available, keeps animation
- AVIF
- effort 4, lossless available — smallest, slowest
- GIF
- animation preserved; usually better converted to WebP
- HEIC
- read only; written back as AVIF
- Colour
- ICC profile always kept; EXIF only on request
- Order
- rotate → crop → resize → encode
Why use SlimFile for this
Never bigger than before
If a compressed image would come out larger, you get the original back, marked "Already small".
Smart mode picks the quality
It compares each result against the original and chooses the lowest quality that still matches, image by image.
Hit an exact file size
Give a target in KB and each image is brought under it — handy for forms with upload limits.
Free, no sign-up
No account, no email address, no trial that runs out.
No watermark
What you download is clean — nothing added to your file.
Deleted within an hour
Uploads and results are removed automatically about an hour after processing. We never look inside them.
Questions
How do I reduce an image to under 100 KB?
Switch from "by quality" to "by file size" and enter 100. Quality is lowered until each image fits, and only if that is not enough is the image scaled down as well.
Does compressing reduce the quality of my images?
Not in any way you are likely to see. Each image is re-encoded at visually lossless settings — mozjpeg quality 80 for JPG, quality 82 for WebP, palette quantisation for PNG — and the metadata is stripped. It is not mathematically identical to the original, but side by side the picture looks the same.
How many images can I compress at once?
Up to 20 images per batch, and each file can be up to 12 MB. You can start a new batch as soon as the current one finishes.
Which formats are supported?
JPG, PNG, WebP and AVIF can all be read and written, and images keep their format unless you ask to convert. HEIC photos from an iPhone can be uploaded, but they are written back as AVIF, because encoding HEIC needs a licensed HEVC encoder. A HEIC that cannot be read is refused with a clear message rather than failing quietly.
What happens if compressing makes the file bigger?
Already-optimised images sometimes come out larger. When that happens the original is kept and the row is marked "Already small", so you never receive a file bigger than the one you uploaded.
Do you keep my images?
No. Compressed files are held in temporary storage so you can download them, and are deleted an hour later. No account is needed and nothing is published anywhere.
Can I resize, convert, rotate or crop as well?
Yes. A quality slider and a resize control apply to the whole batch, and you can convert between JPG, PNG and WebP at the same time. Rotation and crop are per picture — the Edit button on each row opens both together, with aspect presets for common shapes. Everything is applied in the order you would expect: rotate, then crop, then resize, then encode.
My transparent PNG turned black when I converted it to JPG. Why?
JPG cannot store transparency, so every see-through pixel has to become a solid colour. That colour is white by default, and you can change it — a colour picker appears under the settings whenever JPG is the chosen output, with white, black and a couple of greys as presets. Converting to PNG, WebP or AVIF instead keeps the transparency intact.
Will my animated GIF stay animated?
Yes. Animated GIF and WebP keep every frame, and converting between the two keeps them too — WebP is usually far smaller. Rotating or cropping an animation is not possible, because those work frame by frame, so those controls are turned off for animated files. Converting one to JPG, PNG or AVIF produces a still, and the row says so rather than letting you find out later.
What is Smart mode?
Instead of guessing a quality number, it compresses, compares the result against the original, and picks the lowest quality that still matches. A flat graphic might drop to quality 31 with no visible change at all, where a detailed photo needs 85 — one fixed number cannot suit both. It takes longer because it encodes several times.
Can I compress without losing any quality at all?
Yes, for PNG, WebP and AVIF — tick Lossless and every pixel is preserved exactly. Files are considerably larger, but it is the right choice for line art, screenshots and anything you will edit again. JPG has no lossless mode.
Will my copyright and camera information be kept?
Only if you ask. "Keep metadata" retains EXIF, copyright and camera details; it is off by default because that data also includes GPS location. The colour profile is a separate matter and is always kept, so a wide-gamut photo will not shift colour.
Can I compress to a specific file size?
Yes. Switch from "by quality" to "by file size" and give a target in KB. Quality is lowered until each file fits, and only if that is not enough is the image scaled down as well — losing quality is less destructive than throwing away pixels.
Can I see the difference before downloading?
Yes. The compare button on each row shows the original and the compressed version either side of a divider you can drag, with zoom and pan for close inspection and a difference view that highlights exactly which pixels changed. It also measures the similarity — SSIM and PSNR — so "visually lossless" is a number rather than a claim.
Can I export one image at several sizes?
Yes. The export button on each row produces a set of widths in one run — 400, 800 and 1600 by default — and adds them to the batch so they download individually or in the zip. It also gives you a ready-made responsive img tag with the srcset filled in.
Which format should I use?
There is no general answer: a flat graphic and a photograph disagree. Open Edit on any file and use "Which format wins?" — it encodes your actual image to JPG, WebP and AVIF, shows the resulting sizes, and lets you apply the winner to that file alone.
Do I have to set everything up each time?
No. There are presets for common jobs — web hero, email attachment, thumbnail, archive copy — and you can save your own settings as a preset, which is remembered in your browser.
Can I change the file names when downloading?
Yes — open "Edit file names" above the list. By default files keep the names you uploaded. You can also replace them with a name of your own, or use random names, and add a prefix or suffix around either. Numbering can be added at the start or the end, with a chosen starting number and number of digits. A preview shows the result before you download, and the same names are used inside the zip.
Will my photos come out rotated?
No. Orientation from the EXIF data is applied to the pixels before the metadata is removed, so portrait photos from a phone stay the right way up.