One image is easy. A folder of fifty images is where most online tools become annoying. You either upload everything to a server, wait for a queue, download files one by one, or discover that the free plan only allows five conversions. For private photos or client assets, uploading the whole folder is also a trust problem.

A browser-based batch workflow solves both issues. The files are decoded and re-encoded on your device, then bundled into a ZIP for download. You get the convenience of a web tool without handing your entire folder to a remote server.

First, decide the target format for the whole batch. Use JPG when you need compatibility and small photo files. Use PNG when you need transparency or lossless screenshots. Use WebP when the images are going to a modern website and your CMS accepts it. Mixing output formats in one batch is possible in theory, but it makes file management harder.

Second, remove anything that should not be processed. Screenshots, product photos and icons often need different settings. A folder that contains both transparent logos and regular camera photos should usually be split into two batches. That lets you preserve alpha for logos while compressing photos more aggressively.

After conversion, download the ZIP and inspect a few representative files before deleting the originals. Check one large photo, one small graphic and one file with text or transparency. This catches the usual mistakes: transparent backgrounds flattened to white, file names that no longer match your CMS convention, or overly strong compression.

Keep the original folder until the final images are published or delivered. Batch conversion is fast, but the original files are still your source of truth. If you later need a different size, format or quality setting, starting from the original produces cleaner results than converting the converted files again.