Your files stay on your Mac.
Converting Flash (FLV) to AAC pulls the audio track out of your video file and saves it as a standalone AAC file. Convertessa processes everything locally on your Mac — no upload, no internet connection required. Set quality to balance audio fidelity against file size before you convert.
Drag one FLV file or an entire folder of Flash videos onto Convertessa. Batch conversion processes every file in one pass without re-importing.
Choose AAC from the output format list. Set quality to control how much of the original audio fidelity is preserved versus how small the output file is.
Click Convert. Convertessa extracts the audio track from each Flash file and writes it as an AAC file alongside the original. Nothing is uploaded — conversion runs fully on 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.
No. Convertessa runs entirely offline on your Mac. Your Flash files are never sent to a server or cloud service.
Yes. Drop an entire folder onto Convertessa or run convertessa ./folder/ --to aac to batch-convert every FLV file in one pass.
Use the quality slider before you click Convert. Higher quality preserves more of the original audio at the cost of a larger output file.