Your files stay on your Mac.
Convertessa reads your MP4 and rewraps the video and audio streams inside a Matroska MKV container. You can set quality to control output fidelity when a codec pass is applied. Batch mode converts an entire folder of MP4 files in one run — no upload required.
Drag one MP4 or a whole folder onto Convertessa. Files stay on your Mac — nothing is uploaded.
Choose Matroska MKV from the output list. Set quality if you want to control output fidelity during encoding.
Click Convert. Convertessa writes the MKV files to your chosen folder. Resolution is preserved.
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.
Convertessa rewraps the existing video and audio streams into the MKV container without re-encoding when the codecs are compatible. If you set a quality value, a codec pass is applied and the output is re-encoded to that quality level.
Yes. Convertessa preserves the original resolution. The output MKV has the same resolution as the source MP4.
Yes. Drop a folder onto Convertessa or run convertessa /path/to/folder --to mkv from the command line. Every MP4 inside the folder is converted to MKV in one pass.