Organize first
Before applying processing to a large folder, separate photos, screenshots, icons and illustrations. Different types of visual content respond differently to resizing and compression. Consistent naming conventions such as subject-width-format make later uploads and troubleshooting simpler.
Group by intended usage
For article body photos, set a maximum width appropriate to the content area. For thumbnails, crop to your layout aspect ratio. For icons and graphics, preserve transparency if it is required. Processing everything with the same aggressive JPEG settings can damage text-heavy screenshots and small graphics.
Work in manageable batches
Client-side processing is convenient because images do not need to be uploaded to a conversion server. However, browsers have finite memory, and very large input photos can consume far more RAM than their compressed file size suggests. Start with smaller batches, especially on mobile, and keep other heavy applications closed if an export fails.
Verify before replacing files
Inspect at least a handful of representative outputs. Check file dimensions, file types, missing transparency, compression artifacts, and generated names. Compression is not guaranteed to reduce every file, so compare before and after sizes rather than assuming every output will be smaller.
Download and archive
Use per-file downloads when you only need a few final pictures. ZIP downloads help organize a larger batch into one archive, but a ZIP without compression stores already encoded image bytes and should not be expected to shrink JPEG or WebP files further. Retain your original source archive separately.