Your files stay on your Mac.
AMR files store narrow-band voice audio recorded by mobile phones. Converting to Matroska (MKA) repackages that audio into an open, flexible container with broad media-player support. Convertessa does the entire rewrap locally — your recordings never leave your Mac.
Drag one AMR file or an entire folder into Convertessa. Batch mode queues every AMR in the folder and processes them in a single pass.
Choose Matroska (MKA) from the output list. Because MKA supports lossy audio, you can set quality to control encoded fidelity before converting.
Click Convert. Convertessa rewraps each file into MKA entirely offline — no internet connection, no upload, no waiting on a 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.
Yes — the audio is decoded from AMR and encoded into the MKA container. Use the quality setting in Convertessa to control how much fidelity the encoder preserves.
Yes. Drop a folder onto Convertessa or run convertessa ./folder --to mka to batch-convert every AMR file in one pass. Output MKA files are written alongside the originals.
No. Convertessa runs entirely offline. Your AMR recordings are never uploaded — the conversion happens on your Mac.