Your files stay on your Mac.
Emacs Muse is a lightweight plain-text markup language built into Emacs that encodes prose, links, headings, and lists in a human-readable format. Converting to HTML renders that markup as standard web content any browser can display. Convertessa reads your .muse files and writes self-contained HTML output — entirely on your Mac, with no files ever leaving your machine.
Drag one .muse file or an entire folder of them onto Convertessa. Batch mode processes every file in the folder in a single pass.
Pick HTML from the output format list. Convertessa maps Muse headings, paragraphs, links, and inline markup directly to their HTML equivalents.
Click Convert. Convertessa writes one .html file per source document alongside the originals. Nothing is uploaded — conversion runs fully offline 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.
Yes. Muse's heading levels map to <h1>–<h6> tags, hyperlinks become <a href> elements, and inline emphasis carries over as <em> and <strong>. The structure of your document is faithfully reflected in the output HTML.
Yes. Drop a folder onto Convertessa or use the CLI: convertessa ./folder --to html. Every .muse file in the folder is converted in one pass, each producing its own .html file.
Completely. Convertessa runs offline — no files are uploaded to any server. Conversion happens locally on your Mac, so your documents stay private and the tool works without an internet connection.