How do I compress images without losing quality?

Use the Auto mode with quality between 88% and 95%. In formats like WEBP and JPEG, this range significantly reduces file size while keeping the quality visually identical to the original.

What is the difference between lossy and lossless compression?

Lossless compression preserves data pixel-by-pixel — used in PNG. Lossy compression discards barely-perceptible details in exchange for much smaller files — used in JPEG, WEBP and AVIF. At 90%+ quality the difference is virtually invisible.

Why is WEBP usually smaller than JPEG?

WEBP uses a more modern algorithm (VP8/VP9) that delivers, on average, 25% to 35% smaller files than JPEG at the same visual quality, while also supporting transparency.

Are my images uploaded to any server?

No. All compression happens locally in your browser using the Canvas API. No byte is sent to ToolboxHub servers or any third party.

What happens if compression makes the file larger?

When the result is larger than the original (common in already well-optimized images), the tool keeps the original file and marks it as No gain. You never get a worse file than what you uploaded.

Can I compress multiple images at once?

Yes. Add as many images as you want to the upload area — they will all be processed in batch. Use Download all to download everything at once.

Is there a size or file count limit?

There is no limit imposed by the tool. The only practical limit is your device's memory, since everything is processed locally.

How do I compress images to send on WhatsApp?

WhatsApp recompresses images sent from the gallery, losing quality. To preserve quality, compress to WEBP at 90% beforehand and send as a Document — that way WhatsApp won't recompress and the file arrives with the original quality and reduced size.

How do I compress images for email (Gmail / Outlook)?

Gmail accepts attachments up to 25 MB and Outlook 20 MB per message. Use Auto mode at 88-92% to reduce 50-80% of the size while keeping visual quality — that way you can attach several photos without needing Google Drive or OneDrive.

How do I compress images for websites and blogs?

For the web, use WEBP at 80-85% — files are usually 60% smaller than JPG at the same visual quality, improving Core Web Vitals (LCP) and the site's Google ranking. For hero photos, keep 88-92% to avoid visible artifacts.

How do I compress PNG images without losing transparency?

Keep the PNG format (Keep format mode) or use WEBP, which also supports the alpha channel. Avoid JPEG, which replaces transparency with a white background. At 90%+ quality, WEBP usually reduces the size of transparent PNGs by 40-70%.

Free Online Image Compressor: PNG, JPEG, WEBP without losing quality

Free online image compressor

Reduce the size of PNG, JPEG and WEBP with no visible quality loss. All compression happens in your browser, ensuring full privacy — no file is sent to any server. The tool picks the best output format for each image, resulting in the smallest possible file.

How to compress images in 3 steps

Add the images by dragging them into the upload area or clicking to select.
Adjust the quality and choose the output strategy (Auto is recommended).
Click Compress now and download the files individually or in bulk.

Supported formats

Input (8 formats)

PNG
JPEG / JPG
WEBP
GIF
BMP
AVIF
TIFF
HEIC / HEIF

Output (3 formats)

WEBP
JPEG
PNG

Why use ToolboxHub to compress images?

✓ 100% in the browser: no upload, full privacy.
✓ Smart detection: picks the smallest between the original format and WEBP.
✓ Batch compression: many images at once.
✓ Preserved quality: defaults to 92%, with no perceptible visual loss.
✓ No regression: if the result gets bigger, it keeps the original.
✓ Free and unlimited: no signup, no watermark.

Compress Images