Your files stay on your Mac.
Convertessa reads your .au audio files and rewrites them as Apple Core Audio Format (.caf) containers, preserving the original sample rate, bit depth, and channel count. CAF removes the 4 GB file-size ceiling of older formats and is the native container for macOS and iOS audio pipelines. Every file is processed locally on your Mac — nothing is uploaded.
Drag one .au file or an entire folder into Convertessa. The app reads every AU file it finds, including those nested in subfolders.
Choose Apple CAF from the output format list. Convertessa will write each file as a .caf container while keeping the original sample rate, bit depth, and channel layout intact.
Click Convert. Every file is processed locally — nothing leaves your Mac. The resulting .caf files are saved alongside their originals.
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. Convertessa remuxes the audio stream into a CAF container without re-encoding, so the sample rate, bit depth, and channel count are preserved exactly.
CAF is Apple's native audio container and supports files larger than 4 GB, making it the standard format for Core Audio APIs and Xcode audio assets. AU files predate this format and lack those capabilities.
Yes. Run convertessa ./my-folder --to caf and Convertessa converts every AU file it finds inside the folder in one pass.