Your files stay on your Mac.
Converting FLAC to Matroska repackages lossless audio into an MKA container with your chosen quality setting. The Matroska container is widely supported by media players and home-theatre systems that don't accept bare FLAC streams. Files never leave your Mac — conversion runs entirely offline.
Drag one file or an entire folder of FLAC tracks onto Convertessa. Batch mode processes every file in one pass.
Pick Matroska (MKA) from the output list, then set quality to control the encoded audio fidelity.
Click Convert. Convertessa writes the MKA files alongside your originals. Nothing is uploaded; everything stays on disk.
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.
That depends on the quality setting you choose. FLAC is lossless, so the source audio is perfect. Matroska stores the encoded result at whatever quality level you select — higher quality means larger files and less audible difference from the original.
Yes. Drop the folder onto Convertessa or run convertessa ./folder/ --to mka in the terminal. Every FLAC file in the folder is converted in a single batch.
Completely. Convertessa converts files locally on your Mac — no file is ever uploaded to a server or sent over the network.