Question 1

Are my images uploaded to a server?

Accepted Answer

No. This page has no upload endpoint at all — images live in your browser memory from selection to download and vanish when you close the tab. You can even go offline and it keeps working, because nothing is ever requested.

Question 2

Which formats are supported? Why can’t I open HEIC from my iPhone?

Accepted Answer

Input: JPG, PNG, WebP, GIF (first frame), BMP, AVIF. Output: JPG, PNG, WebP, plus AVIF when your browser can encode it. HEIC is Apple’s proprietary codec that browsers cannot decode — export it as JPG from Photos first.

Question 3

How do I process many images at once?

Accepted Answer

Tune one image until you like it, then click “Apply to all” at the bottom of the panel (tick images first to limit it to those). Then use “Batch export” to save them individually or as a ZIP.

Question 4

Why did compression barely shrink my file?

Accepted Answer

Two usual reasons: the output is PNG, which is lossless so the quality slider does nothing — switch to JPG or WebP; or the image is already a heavily optimized JPG, in which case lower the quality below 70% or scale the longest edge to 1920.

Question 5

Why did my transparent background turn white?

Accepted Answer

JPG has no alpha channel, so transparent areas are filled with white on export (otherwise they become black blocks). Choose PNG or WebP to keep transparency.

Question 6

Will a huge 30 MB photo crash the page?

Accepted Answer

Live preview always works on a downscaled canvas, so sliders stay smooth; full resolution is only used at export time. Stay under roughly 40 megapixels per image — beyond that you are limited by device memory.

Question 7

Does it work on mobile browsers?

Accepted Answer

Yes. The layout reflows for phones: preview on top, tools below, image list as a horizontal strip, and every slider supports touch. Safari, Chrome and in-app browsers all work.

Question 8

How far can I undo and redo?

Accepted Answer

Each image keeps its last 30 parameter changes: Ctrl/⌘+Z to undo, Ctrl/⌘+Shift+Z to redo. Note that undo works on settings, not pixels, so every step is lossless.

Online image toolkit