Your files stay on your Mac.
AU is Sun Microsystems' raw audio container, widely used in older Unix and Java environments. AIFF is Apple's native uncompressed audio format, natively read by macOS, Logic Pro, and most professional DAWs. Converting AU to AIFF repackages the audio data into a container that Mac and pro-audio tools open without plugins or workarounds.
Drag one or more AU files onto Convertessa, or use the folder picker to load an entire directory. Files never leave your Mac — everything runs offline.
Choose AIFF from the output format list. Because AIFF is a lossless container, no quality setting is required — the audio data is preserved exactly.
Click Convert. Convertessa processes every file locally and writes AIFF files alongside the originals. Resolution and channel layout are preserved.
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.
No. Both AU and AIFF can store uncompressed PCM audio. Convertessa repackages the audio data into the AIFF container without re-encoding, so the waveform is bit-for-bit identical to the source.
Yes. Drag a folder onto Convertessa or run convertessa /path/to/folder --to aiff from the command line. Every AU file in the folder is converted in one pass.
Convertessa strips embedded metadata during conversion. The output AIFF files contain audio data only, with no residual tags from the source AU container.