Batch Image Compressor by Yoshinya
Ever run images through a bulk compressor and found them more degraded than you expected? Or found that the tools which let you compare before and after only take one file at a time? Batch Image Compressor loads the whole batch at once, so you can compare and adjust each image as you go.
- Free
- No sign-up
- Processed in your browser
🔒 Your images are not sent to a server. All processing happens in your browser.
Guide
How to use the tool
- Drop your images onto the upload area. They are read in your browser and never uploaded.
- The first image opens in the comparison view. Drag the line across it to see the original on the left and the compressed result on the right.
- Adjust the quality until the result still looks right to you. The file size updates as you go.
- Press “Apply quality N to the remaining …” so the images after this one start from the setting you just chose.
- Press Download & next. The image is saved and you move to the next one that still needs attention — or take everything at once with Download all as ZIP.
When is it useful?
- Photos for a website are too heavy and the page is slow to load.
- A form or a marketplace refuses anything over a few megabytes.
- A batch of product shots has to come down in size without visibly degrading.
- You want to see what compression did to each picture before committing to it.
- The images are confidential and uploading them to an online compressor is not an option.
Choosing a quality
Quality 80 is a good starting point for photographs — most of the file disappears while the difference stays hard to see. Detailed textures, text inside an image, and flat illustrations show artefacts sooner, so compare those at 100% zoom before deciding. Below about 60 the damage is usually visible. Above about 90 the opposite happens — the picture stops improving while the file keeps growing — except at exactly 100, where WebP switches to lossless and comes out pixel-identical, often smaller than 99. PNG has no quality setting at all because it is lossless; to shrink a PNG, resize it or convert it to WebP.
Privacy and security
Your images are decoded, compressed, and packed into a ZIP entirely inside your browser. Nothing is uploaded to a server, no account is required, and closing or reloading the page discards everything. Because the images never leave your device, the tool can be used with confidential or personal photos.
Frequently asked questions
- Are my images uploaded to a server?
- No. Every image is decoded and re-encoded in your browser using your own device. No image or filename is sent anywhere.
- Which formats can I use?
- JPEG, PNG and WebP go in, and you can save as any of those or keep the original format. HEIC, AVIF, SVG, GIF and RAW are not supported.
- Why is there no quality slider for PNG?
- PNG compression is lossless, so there is no quality to trade away — a quality setting would do nothing. Resize the image or convert it to WebP to make a PNG smaller.
- Is quality 100 different from 99?
- Very. At 100 the browser encodes WebP losslessly — the result is pixel-identical to the original and is often smaller than quality 99. Between about 90 and 99 the picture barely improves while the file keeps growing, so 99 gives you roughly the loss of 80 at a much larger size. Use 100 when nothing may be lost, and 75–85 when size matters.
- Why did my file get bigger?
- Re-encoding an already-compressed image at a higher quality, or turning a photograph into PNG, can produce a larger file. The tool tells you when that happens rather than hiding it; lower the quality or keep the original.
- Can I use a different quality for one image?
- Yes. Switch the settings to “This image only”, adjust it, and the rest are left alone. That image is then marked as adjusted in the list.
- What does “apply to the remaining” change?
- Only images after the current one that you have not saved yet. Images before it, ones you already downloaded, and ones that failed are never touched, and the notification tells you how many were affected so you can undo it.
- Is the photo metadata kept?
- No. Re-encoding drops the capture location, date, and camera details. For anything you post online, that means your home address is not embedded in the file. If you sort photos by capture date, keep the originals as well. Rotation is applied to the image itself, so nothing comes out sideways.
- How many images can I do at once?
- Up to 100 images, 30 MB each and 300 MB in total. The real limit is your device’s memory, so very large photos are best done in smaller batches.