Comparison · Browser-only image tools
Both Convertissima and Squoosh run entirely in your browser and never upload your files — that is the shared, private foundation. The difference is focus. Squoosh is the better tool when you want to squeeze one image as small as possible with hands-on codec controls and a live before/after slider. Convertissima is the better tool when you need to batch-convert many files, export a multi-size .ico favicon, or convert a PDF to an editable Word document — none of which Squoosh does.
Pick by the job in front of you — they are complementary, not interchangeable.
You want to optimize a single image with precise codec settings (MozJPEG, WebP, AVIF, OxiPNG, and more), compare quality side-by-side with the visual slider, and chase the smallest possible file size. It is an excellent image-compression playground from the Google Chrome Labs team.
You need to convert many files at once, generate a multi-size .ico favicon from a PNG or JPG, output GIF or an SVG raster wrapper, or turn a PDF into a Word (.docx) file — including scanned and image-only PDFs. All in the browser, no account.
Both are free, client-side, and require no sign-up. Here is where they diverge.
| Capability | Convertissima | Squoosh |
|---|---|---|
| Runs fully in the browser (no upload) | Yes | Yes |
| Free, no account | Yes | Yes |
| Works offline after load (PWA) | Yes | Yes |
| Batch queue (many files at once) | Yes | No — one image at a time |
| Multi-size ICO favicon export (16–256 px) | Yes | No |
| GIF output | Yes | No |
| SVG container (raster wrapped in SVG) | Yes | No |
| PDF to Word (.docx), scans included | Yes | No — image-only tool |
| Core formats: JPG, PNG, WebP, AVIF | Yes | Yes |
| Advanced per-codec compression controls | Quality slider + resize | Yes — deep encoder settings |
| Live before/after visual comparison | No | Yes |
| JPEG XL / cutting-edge experimental codecs | No | Yes |
| Quality / resize controls | Yes | Yes |
Same privacy model, different sweet spots.
Squoosh is a compression specialist. If your goal is to take one hero image and tune it byte-by-byte — switching codecs, nudging quality, and watching a live diff — Squoosh is hard to beat. Its advanced encoder controls and experimental formats like JPEG XL go further than most converters.
Convertissima is a conversion workhorse. Most everyday tasks are not "perfect one image" — they are "convert these twelve screenshots to WebP," "make a favicon from this logo," or "turn this scanned PDF into something editable." Convertissima handles those with a batch queue, real multi-size ICO export, and an in-browser PDF-to-Word tool, while keeping the same no-upload, no-account privacy guarantee.
Bottom line: use Squoosh to optimize a single image; use Convertissima to convert batches, build favicons, and handle PDFs — all without your files ever leaving your device.
Convertissima vs Squoosh, answered directly.
Yes, for different jobs. Squoosh is best for tuning compression on a single image with a live before/after preview. Convertissima is the better choice for batch conversion, multi-size .ico favicons, GIF/SVG output, and PDF to Word. Both run entirely in the browser with no upload.
No. Both decode and encode locally in the browser tab. No file is sent to a server in either product, and neither requires an account.
No — Squoosh is image-only. Convertissima also converts PDF to Word (.docx) in the browser, including scanned and image-only PDFs.
No. Squoosh does not export the Windows .ico format. Convertissima builds a real ICONDIR with PNG payloads at 16, 32, 48, 64, 128 and 256 px from a JPG or PNG, using progressive downscale for sharp small icons.
Squoosh is built around optimizing one image at a time. Convertissima provides a batch queue: drop many files, pick one output format, and convert them in sequence.
Batch image conversion, multi-size favicons, and PDF to Word — all in your browser, no sign-up.