Your files stay on your Mac.
Convertessa re-encodes Windows Media (WMV) files into the open WebM format, producing video ready for modern browsers and web playback. The entire conversion runs locally on your Mac — no account, no upload, no waiting on a server. Set quality to trade file size against visual fidelity before you convert.
Drag one WMV file or an entire folder of WMV files onto Convertessa. Batch mode queues every file at once — no need to convert one at a time.
Pick WebM from the output list. Set quality to control the balance between file size and visual fidelity — Convertessa re-encodes to VP9/Opus inside the WebM container.
Click Convert. Convertessa processes every file on your Mac, preserving resolution throughout. Converted WebM files land in the folder you choose.
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. Convertessa runs entirely on your Mac. Your WMV files are never sent to a server — conversion happens locally and finishes without an internet connection.
Yes. Drop a folder onto Convertessa or point the CLI at a directory with --to webm. Every WMV inside is queued and converted in one pass.
WebM uses a lossy codec, so quality affects both file size and visual fidelity. A higher setting produces a larger, sharper file; a lower setting produces a smaller file with more visible artefacts. Start with the default and adjust to taste.