Your files stay on your Mac.
MKV is a container that bundles video, audio, and subtitle streams into a single file. This conversion extracts the primary audio stream and re-encodes it using the Opus codec — an open, patent-free format built for high-quality audio. Convertessa runs the entire process locally on your Mac; nothing is uploaded.
Drag one file or a whole folder of MKV files onto Convertessa. Batch mode processes every file in one pass without repeating setup.
Select Opus from the output format list. Because Opus is a lossy format you can set quality before converting — higher values give better fidelity, lower values give smaller files.
Click Convert. Convertessa extracts the audio track from each MKV and writes a .opus file alongside it — entirely on your Mac, no upload required.
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.
No. Opus is an audio-only format. Convertessa extracts the primary audio track from the MKV container and encodes it as Opus; the video and subtitle streams are not carried into the output file.
Yes. Opus is a lossy format, so Convertessa lets you set quality before converting. Raise it for better fidelity, lower it for smaller files. The default setting works well for most listening scenarios.
No. All conversion happens locally on your Mac using Convertessa's offline engine. Your files never leave the machine, which makes it suitable for private or sensitive recordings.