Your files stay on your Mac.
FLAC stores audio without any data loss; Apple M4A (AAC) re-encodes it at a quality level you choose, producing files that are substantially smaller and natively supported by iTunes, Apple Music, and every iOS and macOS app. The entire conversion runs on your Mac — no file ever leaves your machine.
Drag individual FLAC files or an entire folder into Convertessa. The app queues everything at once, ready for batch conversion.
Pick Apple M4A from the output format list. Use the quality slider to set the AAC quality level — higher quality preserves more detail; lower quality produces smaller files.
Click Convert. Convertessa re-encodes each file locally and saves the M4A output alongside the 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.
Yes. Apple M4A (AAC) is the native audio format across iOS, iPadOS, macOS, and tvOS, so converted files play in the Music app and any third-party audio player without installing extra codecs.
Use the quality slider before converting. Lower settings produce smaller M4A files; higher settings preserve more of the original FLAC detail at the cost of a larger file.
Yes. Drop the entire folder onto Convertessa and it queues every FLAC file inside. The CLI equivalent is convertessa *.flac --to m4a run from the album directory.