Your files stay on your Mac.
GIF encodes animation as a sequence of palette-limited frames — a 256-color ceiling that inflates file sizes. WebM wraps those frames in a VP9 video stream that compresses far more efficiently and supports full 24-bit color. Convertessa decodes each GIF frame-by-frame and encodes the result as a WebM file entirely on your Mac, nothing uploaded.
Drag individual GIFs or an entire folder into Convertessa. All .gif files in the folder are queued for conversion in one batch.
Choose WebM from the output format list, then set quality to balance visual fidelity against file size — higher values preserve more detail.
Click Convert. Convertessa decodes each GIF and writes a WebM file alongside the original. No network connection needed.
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. Because WebM is a lossy format, Convertessa lets you set the quality level before converting. A higher value keeps more detail at the cost of a larger file; a lower value compresses more aggressively. The default setting works well for most GIF animations.
Yes. Convertessa reads each GIF frame's delay value and encodes the WebM with matching frame timing, so the animation plays back at the same speed as the source file.
Yes. Drop a folder onto Convertessa and it queues every GIF inside for conversion. You can also use the CLI: convertessa ./gifs --to webm converts all GIFs in the folder in one pass.