About

About & contact

Why this exists

Most online image compressors ask you to upload private photographs to a server you know nothing about, then hand back a watermarked file behind a queue. Browsers have been able to decode, resize and re-encode images locally for years. UnderKB does exactly that: the work happens on your device, at your device's speed, and your files never leave it.

How it works

Images are decoded with createImageBitmap, resampled at high quality, and re-encoded through an OffscreenCanvas running in Web Workers so the interface stays responsive. In target-size mode a binary search finds the highest encoder quality that still fits under your limit, and falls back to reducing dimensions when quality alone is not enough — never to the quality floor, so a small file does not also mean a badly degraded one.

What it does not do

There is no account, no queue, no watermark and no upload limit, because there is no server to impose one. The practical ceiling is your own device's memory. Re-encoding also strips all metadata, including GPS coordinates, which is usually what you want before sending a photograph to a stranger.

What's next

An A4 poster splitter for tiling a large image across printable pages, and a batch format converter. Both will follow the same rule: nothing gets uploaded.

Contact

Bug reports, feature requests and partnership enquiries are all welcome at valae.entreprise@gmail.com. We aim to reply within a few working days.