Your files stay on your Mac.
WAV stores audio as raw PCM — lossless but large. M4A wraps AAC-encoded audio in a container that Apple devices, iTunes, and QuickTime read natively, cutting file size dramatically while preserving perceived fidelity. Convertessa runs the conversion entirely on your Mac: no upload, no account, no round-trip to a server.
Drag one WAV file or an entire folder of WAVs onto Convertessa. Batch mode processes every file in one pass.
Pick Apple M4A from the output list. Because M4A uses AAC compression, you can also set quality — dial it up for archival copies or down to shrink podcasts and voice memos.
Click Convert. Convertessa writes .m4a files alongside your originals. Nothing is uploaded — the conversion runs locally on your Mac.
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 data is discarded — but at high quality settings the difference is inaudible to most listeners. Because WAV is the lossless source, Convertessa starts from the full signal with nothing pre-compressed.
Yes. M4A (AAC) is the native audio format across Apple platforms and is supported by iOS, iPadOS, macOS, tvOS, iTunes, and the Music app without any additional codecs.
Yes — drag the folder onto Convertessa or use the CLI: convertessa ./folder --to m4a. Every WAV file in the folder is converted in a single batch.