Convert many images at once, free

Choosing the right output format

Pick JPG when you need maximum compatibility and the images are photos. JPG opens in every app, viewer, and form on earth, and it compresses photos well. Its one limitation is transparency, which it cannot store, so it flattens any see-through areas onto white.

Pick PNG when you need lossless quality or you have flat graphics, logos, and screenshots with crisp text. PNG keeps every pixel exact and preserves transparency, at the cost of larger files for photographic content. It is the safe choice when edges must stay sharp.

Pick WebP when you want smaller files than JPG while keeping transparency and broad support. WebP is read by every current browser, compresses better than both JPG and PNG, and keeps the alpha channel, which makes it a strong all-round default for the web.

Pick AVIF when you want the smallest possible files for a modern site and you can serve a fallback. AVIF beats WebP on size and keeps transparency, but it is newer, so older software and some forms cannot read it. The converter handles AVIF encoding on every browser, falling back to a built-in encoder where needed.

What happens to transparency across a batch

Transparency is the one feature that behaves differently depending on the target, so it deserves a moment's thought before you convert a mixed batch. Some of your sources, the PNGs and WebPs, may carry an alpha channel; the JPGs never do.

If you convert the batch to JPG, every transparent area in every file is filled with white, because JPG has no way to store transparency. For photos and screenshots that is invisible and fine. For logos and cutouts that were meant to float over a colour, it produces a white box.

If you convert to PNG, WebP, or AVIF, transparency is preserved wherever it exists. A transparent PNG stays transparent, and a flat JPG simply has no transparency to carry, so it converts cleanly either way. These formats are the safe targets when the batch contains cutouts you care about.

The practical rule: if any file in the folder relies on a transparent background, avoid JPG as the target. Choose WebP for the best mix of size and support, or AVIF for the smallest files, and the whole batch keeps its transparency without you having to sort the files first.

Quality and how it applies to every file

For the lossy targets, JPG, WebP, and AVIF, a single quality setting applies to the whole batch. That keeps the output consistent: every converted file lands at the same quality level rather than each one being a guess. PNG ignores the setting because it is always lossless.

A quality around 85 is a sensible default for a mixed batch headed to JPG or WebP, high enough that photos and screenshots stay clean. For AVIF you can go lower, around 75, because the format holds quality better and you still get a clearly smaller file.

If the batch is purely photographic and bound for the web, you can push the setting down to compress harder, since photos forgive lossy compression. If it contains screenshots or graphics dense with small text, keep it higher, because hard edges show artifacts first.

Because the same setting covers the whole queue, you tune it once and the entire folder follows. There is no need to babysit individual files, which is the entire point of converting in bulk rather than one at a time.

Why converting in the browser is fast and private

Every file is converted on your own device. Your browser decodes each image, redraws it onto a canvas, and encodes it in the target format, then bundles the results into a ZIP. The originals never leave your machine, so there is nothing to upload and nothing to wait for.

Speed comes from parallelism. Rather than sending files to a server and waiting in a queue, the converter spreads the batch across your CPU cores and works on several images at once. A folder of ordinary web images converts in seconds; large photos and AVIF targets take a little longer because they are heavier to encode.

Privacy is a direct consequence of the local design. Since no image is uploaded, none of your files sit on someone else's server, get logged, or risk being cached online. This matters for documents, ID scans, private photos, and any client work under a confidentiality agreement.

There is also no account, no watermark, and no per-file fee. The tool is free because it uses your machine's resources rather than renting servers, which means you can run batch after batch without hitting a quota.

Common bulk conversion jobs

Normalising a phone photo dump is the classic one. A folder of iPhone HEICs that will not open on a Windows machine or upload to an older form converts to JPG in a single pass, and the whole set becomes universally readable.

Preparing a website's images is another. A designer hands over a mix of PNGs and JPGs, and you want everything as WebP or AVIF to keep pages light. Drop the lot, pick the modern format, and the entire media set is converted consistently for the build.

Meeting a submission requirement rounds it out. A portal, a print shop, or a client demands one specific format for a whole set of files. Instead of converting each by hand, you normalise the batch to the required format at once and submit with confidence that nothing is in the wrong format.

Across all of these, the workflow is the same: gather the mixed folder, drop it, choose one target, and download a uniform ZIP. If you also need each file at a specific size afterward, the compress-to-size and bulk compressor tools take the converted set the rest of the way.