Your files stay on your Mac.
Convertessa reads each AAC file on your Mac and re-encodes the audio stream as MP3. You choose the output quality before the conversion runs. Nothing is uploaded — all processing happens locally on your machine.
Drag individual .aac files or an entire folder into Convertessa. Add as many files at once as you need — batch conversion runs in a single pass.
Choose MP3 from the output format list, then set your preferred quality level. Higher quality produces larger files; lower quality produces smaller ones.
Click Convert. Convertessa re-encodes each AAC file to MP3 on your Mac — no upload, no internet connection required.
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.
Yes. Because MP3 is a lossy format, Convertessa lets you choose the output quality before converting. Higher quality retains more audio detail and produces larger files; lower quality produces smaller files.
Yes. Drop a folder onto Convertessa or pass a directory to the CLI: convertessa ./music/ --to mp3. Every AAC file inside is converted in one run.
No. Convertessa writes new MP3 files and leaves your source AAC files untouched.