Question 1

How do I compress an image?

Accepted Answer

Drop one or more images onto the upload area, or click to select them. Adjust the quality slider and output format, then download the result individually or as a ZIP. Compression happens in your browser as you change settings.

Question 2

What image formats are supported?

Accepted Answer

JPEG, PNG, and WebP in, and any of the three out. HEIC files from iPhones aren't supported, because browsers can't decode them — convert to JPEG first and the tool will tell you if a file can't be read.

Question 3

Does compression reduce quality?

Accepted Answer

With lossy formats (JPEG, WebP) yes, so use the quality slider to find the balance you want — 70-80% usually gives a large size saving with little visible difference. PNG is lossless, so the quality slider does not apply and is disabled when PNG is selected.

Question 4

What happens to transparency?

Accepted Answer

WebP and PNG keep the alpha channel. JPEG has no transparency at all, so transparent areas are flattened onto white rather than becoming black. Choose WebP if you need a small file that keeps its cut-out.

Question 5

Can I compress multiple images at once?

Accepted Answer

Yes. Add as many as you like — they all use the same settings, and changing a setting re-compresses the whole batch. Download them one at a time or bundled as a ZIP, where duplicate filenames get a numeric suffix instead of overwriting each other.

Question 6

What are the size limits?

Accepted Answer

Each image can be up to 50 MB. Very high-resolution photos (above roughly 16 megapixels) exceed what browsers can draw to a canvas — set a max width or height and the tool will scale them down first rather than failing.

Question 7

Is my data safe?

Accepted Answer

Compression happens entirely in your browser using the Canvas API. Your images are never uploaded to any server, and nothing is stored after you leave the page.

Image Compressor

Frequently asked questions