Your files stay on your Mac.
AU (Sun/NeXT audio) and AIFF share the same uncompressed PCM core, so converting between them rewraps the audio data into a new container without touching a single sample. Convertessa reads your AIFF files, writes AU files at the same bit depth and sample rate, and strips embedded metadata in the process. Everything runs locally — no file ever leaves your Mac.
Drag one AIFF file or an entire folder into Convertessa. Batch mode processes every .aiff file in the folder in one pass.
Pick AU from the output format list. Convertessa preserves the original sample rate, bit depth, and channel layout — no quality settings are needed because AU is a lossless format.
Click Convert. Your AU files appear beside the originals instantly, ready to use on Unix, Linux, or any AU-compatible host. Source AIFF 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.
Yes. Both AIFF and AU store uncompressed PCM audio, so the conversion is bit-for-bit equivalent. The container changes; the audio data does not.
Yes. Convertessa removes embedded metadata (such as AIFF markers or ID tags) when writing the AU output. The resulting file contains only raw audio data and the AU header.
Yes. Drop the folder onto Convertessa or run convertessa ./folder/ --to au in the terminal. Every AIFF file in the folder is converted in a single batch, and the AU files are written to the same directory.