Your files stay on your Mac.
Opus is an open-source audio codec designed for low-latency speech and high-quality music streaming, stored in .opus files. Convertessa reads those files locally on your Mac and converts them to 13 formats — including MP3, AAC, FLAC, and WAV — without uploading anything to a server.
Drag a .opus file into Convertessa, or click to browse. Drop a whole folder to queue multiple files at once.
Choose MP3, AAC, FLAC, WAV, OGG, or any of the 13 supported output formats from the output list. Set quality when converting to a lossy target.
Hit Convert. Convertessa processes every file locally; nothing is sent to a server. Find your converted files in the destination folder.
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. Drop a folder onto Convertessa or run convertessa /path/to/folder --to mp3 in the terminal. Every .opus file in the folder is converted in one pass.
Transcoding between two lossy formats involves some generation loss. You can set the quality level for the MP3 output before converting to control the trade-off.
Choose MP3 or AAC from the output list — both play on virtually every device and media player. Set quality to balance file size and audio fidelity.