Drop files on Transform, pick a tool that fits them, and press the button. Every tool runs on this Mac; nothing is uploaded.

Built into Ledge for macOS.
Shrink pictures, video, audio and PDFs, or turn them into the format you need.
Trim, rotate, remove a background or a video's sound, make a GIF, or combine files into a PDF.
New files are named (Transformed). A compressed file that isn't smaller is thrown away.