About ImageAlchemy

What we built

ImageAlchemy is a browser-based image compression studio. It converts and compresses images to AVIF, WebP, JPEG and PNG using the same professional codecs as desktop tools — MozJPEG, libwebp, OxiPNG and the AV1 encoder — compiled to WebAssembly and running locally on your own device.

That means you get desktop-grade encoding without installing anything, and without your files ever leaving the machine you are sitting at. Batch up to 200 images at a time, fine-tune quality per image or across the set, and download the results individually or as a single ZIP.

Why privacy first

Most online image tools upload your files to a server. That means your images — and your clients' images — sit on someone else's machine, subject to a retention policy you cannot audit and a breach you would never hear about promptly.

ImageAlchemy inverts that. There is no server that could lose or leak your files, because there is no server in the image path at all. This is not a policy we promise to uphold; it is a property of how the tool is built, and it is the single most important design decision in the project.

The practical consequence is that the tool is usable for work that a cloud converter is not: confidential client photography, unreleased product shots, medical or legal imagery, and anything under an NDA.

How it works

When you drop a file, it is decoded and re-encoded by WebAssembly codecs inside your browser. Batch processing runs across Web Workers so the interface stays responsive, with pause, resume and cancel. Auto-Pick encodes each image as AVIF, WebP and JPEG in parallel and keeps the smallest result, which removes the guesswork about which format wins for a given picture.

Because the codecs are the same ones the professional ecosystem uses, the output is the output you would get from a command-line tool — just without the terminal, and without a round trip to anyone's server.

What actually makes it different

Format support and quality sliders are table stakes; most tools have them. The differences that matter are structural:

No upload path. Not "we delete your files after an hour" — there is no upload step to delete anything from.

No account, no quota, no watermark. There is nothing to sign up for and no artificial limit designed to push you toward a paid tier. The free tool is not a demo of the paid one.

Real encoders, not re-wrappers. MozJPEG, libwebp, OxiPNG and AV1 — the same libraries behind professional pipelines.

Honest numbers. Where the site quotes a saving, that figure came from an actual encode you can reproduce. The comparison demo on the home page is two genuine files, and the build fails if the measured difference collapses.

Who's behind it

ImageAlchemy is built by Alexios Papaioannou, a digital entrepreneur and full-stack creator who builds and operates web products. The tool started as a practical answer to a recurring problem — needing to compress images for client work without handing those images to a third-party service.

The project is developed in the open and the source is available. If you find a bug or a claim on this site that does not hold up, that is worth reporting, and it will be fixed rather than reworded.

How to judge the claims on this site

Every performance or savings figure published here is either measured at build time or attributed to published research, and the site distinguishes between the two. Where a number is modelled rather than measured, it is labelled as such — the quality explorer on the guides is the clearest example.

This matters because image compression is a category full of invented statistics. If a claim on this site cannot be traced to a measurement or a cited source, treat that as a defect and tell us.