FAQ
Frequently asked questions
Everything you might want to know about how Lean Image works — and why your images stay private.
Is Lean Image really free?
Yes — completely free. There is no sign-up, no usage limit, no watermark, and no paywall. You can use it for personal projects and commercial work alike.
Are my images uploaded to a server?
No. Lean Image does all of its work inside your browser. Your images are never transmitted anywhere — there is no server to upload them to.
Do you store my images?
No. Because your images are never sent to us, there is nothing for us to store. They exist only in your browser’s memory while you work, and are gone when you close or refresh the tab.
Which image formats can I use?
You can convert to WebP, AVIF, PNG, JPEG, and GIF. On the way in, Lean Image reads JPEG, PNG, WebP, GIF, AVIF, HEIC, JPEG XL, BMP, TIFF, and SVG — including the HEIC photos an iPhone shoots.
What is the best format for the web?
WebP is the best all-round choice today: excellent compression with near-universal browser support. AVIF compresses even smaller and is great for photos when you want the smallest possible files. Use PNG when you need lossless quality or transparency, and JPEG for maximum compatibility.
Can I compress an image to a specific file size?
Yes. Turn on the maximum file size option and enter a target. Lean Image automatically searches for the highest quality that still fits under your target, and will reduce dimensions if needed to get there.
Is there a file size or image count limit?
There is no artificial cap. You can batch many images at once; the practical limit is your device’s memory. Very large files (roughly 50MB and above) may process more slowly.
Does it work offline?
Largely, yes. Once the page has loaded, the core tool runs without a connection. Some codecs (such as the AVIF encoder) load on first use, after which your browser can keep them cached.
Which browsers are supported?
Any modern browser — Chrome, Edge, Firefox, and Safari. On older versions of Safari that lack OffscreenCanvas, processing falls back to the main thread, which is a little slower but still fully private.
Do you use cookies or track me?
No advertising or tracking cookies, and no analytics scripts. The only thing saved is your own preferences (like format and quality), stored locally in your browser and never sent anywhere.
How is image quality controlled?
A quality slider lets you balance size and fidelity for lossy formats (JPEG, WebP, AVIF). PNG and GIF are lossless, so quality is fixed and the slider is disabled for them.
Can I use Lean Image for commercial work?
Yes. There are no licensing restrictions on the images you optimize with it.