Your files stay on your Mac.
Convertessa reads the audio stream from your MPEG file and rewraps it as an Apple M4A — AAC audio inside an MPEG-4 container. The result plays natively on every Apple device and in Music.app without sending anything to the internet. You can set quality and process a whole folder in one pass.
Drag one or more .mpeg files onto Convertessa. The app reads each file locally — nothing is uploaded or sent anywhere.
Choose Apple M4A from the output list. Set your preferred quality level — a higher value preserves more detail in the compressed AAC stream.
Click Convert. Convertessa writes an .m4a file alongside each original. Your MPEG files are left untouched.
Images, audio, video, documents, archives and eBooks — all converted natively, right on your Mac.
Pick a format you have — see everything Convertessa can turn it into.
Convert hundreds of files at once with per-type group defaults and individual overrides.
First-class support for HEIC, AVIF and WebP — encode and decode, both ways. Read JPEG XL and a dozen more modern formats too.
Drop files anywhere on the window. Native, instant, and exactly what you’d expect on a Mac.
Dial in compression, resolution and bitrate. Keep originals pristine or shrink for sharing.
Never overwrite a file by accident. Convertessa appends safe suffixes automatically.
Every job is logged locally. Re-run a previous conversion or revisit recent outputs in a click.
Bundle your converted files straight into a single ZIP, TAR or 7z — packaged and ready to share the moment a job finishes.
Right-click any file in Finder and choose Convert. A Quick Action handles it on the spot — no need to open the app first.
Shrink Convertessa to a tidy mini window that tucks into a corner — just a drop zone and a format picker for quick, one-off conversions.
No cloud. No account. No upload. Every conversion happens entirely on-device, using the power already in your Mac. What you convert is nobody’s business but yours.
Script conversions, wire them into your build, or batch a folder from the terminal. The same engine, no GUI required.
Read the full CLI documentation →Shrink Convertessa down to a small, focused window — drop, convert, done, with your recent conversions one click away.
macOS 14+ · Apple Silicon & Intel
New formats, new features, and fixes — every release, on the record.
Apple M4A uses AAC, which is a lossy format. Convertessa lets you set the quality level before converting so you control how much compression is applied to the audio stream.
Yes. Drop a folder onto Convertessa or use the CLI batch command and every MPEG file inside is converted to Apple M4A in one pass — no upload required.
Apple M4A (AAC in an MPEG-4 container) is the native audio format for Apple devices and is fully supported by Music.app, iTunes, and iOS without any additional software.