Sideways photos, fixed for good
Phones save the way they were held as a small orientation note inside the photo. Some programs, upload forms and older viewers ignore that note, so the picture shows up sideways. This tool applies the orientation first and then your rotation, and saves the pixels the right way round, so the image looks the same everywhere.
JPG files are saved at high quality (95), PNG stays lossless. HEIC and AVIF photos are saved as JPG, because browsers cannot write those formats.
Batch rotation
Drop a whole set of scans or photos taken with the camera upside down, choose the rotation once and download them all together as a ZIP.