MiniPx vs Optimizilla — Measured Side by Side — Free, Fast & Private
Optimizilla, which now lives at imagecompressor.com, is deservedly popular: it is free, it needs no account, the interface is uncluttered, and the per-image quality slider with live preview is genuinely good — you can see exactly what you are trading before you download.
Both tools compress in the browser. Optimizilla’s page says “All image processing happens entirely in your browser using WebAssembly technology”, and in our October 2026 benchmark its request log showed no file being sent. The differences are elsewhere: with the network switched off it compressed 0 of 2 files and MiniPx compressed 2 of 2; MiniPx reads more formats; and the defaults differ — across the 20 test files Optimizilla’s median output was 61.5% smaller and MiniPx’s 85.8% smaller, with Optimizilla keeping more detail (median SSIM 0.993 against 0.983).
Batch size, honestly stated
Optimizilla’s page states no cap on how many images you drop at once and promises “no daily limits”. MiniPx’s free tier handles 5 files per batch, and Pro removes the cap entirely. So for a one-off batch of holiday photos, Optimizilla is the more convenient free option and it would be silly to pretend otherwise.
The calculation changes when the work is repetitive or the batches are large: MiniPx Pro has no per-batch ceiling at all, and a 300-file batch is limited by your processor rather than your connection.
Formats
Optimizilla takes JPEG, PNG, WebP, GIF and SVG. MiniPx reads HEIC, TIFF, BMP and AVIF as well, and writes JPEG, PNG, WebP or AVIF. If your input is an iPhone HEIC or you want AVIF out, that is the practical difference — not a marginal one, since HEIC is what most iPhones produce by default.
Where offline matters
For a photograph of a sunset, it does not. For a scan of a passport, a medical letter, a signed contract or unreleased product photography, you may want to check for yourself that nothing leaves the machine. The simplest check is to switch the network off and compress: MiniPx kept working in our test, and Optimizilla did not, so on that tool you have to rely on its own statement and a request log instead. MiniPx’s compressor has no upload path.
Competitor details checked October 2026. Plans and limits change — verify against their own pricing page before deciding. Other comparisons: ImageResizer.com · ShortPixel and its credit model · remove.bg