MB to KB Converter is a free browser tool that shrinks a photo to a target size in KB. Pick a JPG, PNG or WebP image and set a size such as 20, 50, 100 or 200 KB. The tool searches for the highest JPEG quality that fits, then reduces pixel dimensions if needed. Batch processing handles up to 20 photos with a ZIP download.
The site says it is free with no sign-up, and that files are processed in your browser and never uploaded; it suggests an offline test so you can check this yourself. No paid tier is mentioned. The FAQ notes that advertising or analytics scripts may be switched on. Companion tools on the site include PDF-to-KB, a signature resizer, a KB/MB unit converter and a 20KB photo tool.
Online forms often demand a photo, signature or PDF under an exact KB limit. The builder made this so people can hit that size quickly in their browser.