Your files stay on your Mac.
Convertessa re-encodes your lossless FLAC audio into Opus, a modern lossy codec built for efficient storage and streaming. You control the quality level, deciding how much file size to trade for fidelity. Conversion runs entirely on your Mac — nothing is uploaded, and metadata is stripped from every output file.
Drag one FLAC file or an entire folder onto Convertessa. Every track appears in the queue, ready to convert.
Choose Opus from the output format list. Set the quality level to dial in the balance between file size and audio fidelity.
Click Convert. Convertessa encodes each file locally and saves the Opus output alongside your originals — your audio never leaves your Mac.
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 — Opus is a lossy format, so some audio data is discarded during encoding. Convertessa lets you set the quality level before converting: higher quality preserves more detail at the cost of a larger file.
No. Convertessa strips metadata from output files, so the resulting Opus files contain audio only, with no embedded tags or cover art.
Yes. Drop a folder onto Convertessa or run convertessa ./album --to opus in the terminal and every FLAC file in that folder is converted in a single pass.