Your files stay on your Mac.
Apple CAF is a lossless container built for iOS and macOS development toolchains, but few media players and no streaming services accept it. Converting to M4A packages the audio as AAC inside an MPEG-4 container — the format iTunes, QuickTime, and every iPhone expect. Convertessa runs the entire conversion on your Mac; your audio files never leave the machine.
Drag one CAF file or an entire folder into Convertessa. Batch conversion processes every file in the folder in one pass with no extra steps.
Choose Apple M4A from the output format list. Because M4A uses AAC encoding you can set quality before converting to balance file size against audio fidelity.
Click Convert. Convertessa encodes each file locally — no network connection needed, no upload, no waiting on a remote server.
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.
M4A uses AAC, a lossy codec, so some audio information is discarded during encoding. You can set quality in Convertessa before converting to control the trade-off between file size and fidelity. For archival work, keep the original CAF files.
Yes. Drop a folder onto Convertessa or point the CLI at a directory and every CAF file inside is converted in one pass. You can also use convertessa ./folder --to m4a to run batch conversion without opening the app.
CAF is a low-level container designed for Apple's audio development toolchain, not consumer playback. It is not supported by most media players, streaming services, or non-Apple devices. M4A is the standard Apple audio format for distribution and plays natively on every Apple device, in iTunes, and in most third-party players.