Aegisub is a free, open-source subtitle editor for Mac (and Windows/Linux) that gives you frame-accurate timing control, a built-in video preview, and a powerful scripting engine — all in one desktop application.
What is Aegisub?
Aegisub is a professional-grade subtitle authoring tool used by fansubbing groups, independent filmmakers, and localization teams worldwide. Unlike the subtitle export tacked onto most video editors, Aegisub is built exclusively around the subtitle workflow — every pixel of its interface exists to help you get captions timed, styled, and positioned exactly right. It works natively with the Advanced SubStation Alpha (.ass) format, the richest open caption format available, while also supporting the ubiquitous .srt and other common standards.
The project lives at TypesettingTools/Aegisub on GitHub and is actively maintained by the community that grew out of the anime fansubbing scene — people who care obsessively about typesetting quality. That heritage shows: no other free tool comes close for precise per-line timing or per-character styling.
What does Aegisub do best?
Aegisub excels at frame-accurate subtitle timing against a live video preview — something most free tools fumble badly. You load your video, scrub through it in the built-in player, and snap subtitle start and end points to exact frames rather than eyeballing millisecond fields. The waveform audio spectrum display underneath the timeline makes dialogue boundaries visually obvious, so you can place cue points by sight rather than trial and error.
Styling depth is where it leaves every competitor behind. The .ass format supports per-line fonts, colours, borders, shadows, rotations, and κaraoke-style character-by-character timing — and Aegisub exposes all of it through a GUI that, while admittedly dense, rewards learning. When I needed to match on-screen Japanese signage for a short documentary, Aegisub let me position a styled text block with pixel precision and composite-preview it against the real frame. Final Cut Pro's caption track couldn't touch that level of control.
- Frame-accurate A/V sync — drag cue points directly on the waveform
- Full .ass styling — fonts, colours, borders, shadows, transforms per line
- Automation scripting — Lua macros for batch timing fixes and style operations
- Translation assistant — side-by-side original/translated text for localisation workflows
- Spell-check and find/replace — basic but solid editorial tooling
Is Aegisub free?
Yes — Aegisub is completely free to download and use, with no feature gating, no subscription, and no watermarks on output files. It is open-source software distributed under the BSD licence. There is no paid tier; the project is sustained entirely by volunteer contributors.
Who should use Aegisub?
Aegisub is the right choice for anyone who needs genuine subtitle authoring power rather than a basic caption overlay. It shines for fansubbers and anime translation groups, independent documentary makers who need accessible closed captions, localization professionals building bilingual subtitle tracks, and educators creating captioned instructional videos. If you just need to slap an .srt onto a YouTube upload and you're fine with auto-timing tools, something lighter like Subtitle Edit (Windows) or even a quick online editor will serve you faster. But the moment you need style control, complex positioning, or frame-accurate timing on a Mac without paying for a commercial tool, Aegisub is the answer.
The learning curve is real — the first hour feels like reading a cockpit manual — but the payoff is a workflow that professionals at post-production houses pay serious money to replicate with commercial software.
How does Aegisub compare to alternatives?
On Mac, your realistic free alternatives are Subtitle Edit (Windows-only natively, so Wine or VM required), Jubler (Java-based, sparse maintenance), and the caption export in DaVinci Resolve (capable but buried inside a full NLE). Among commercial options, Annotation Edit and Subtitle Workshop offer more polish but cost money. Aegisub sits in its own category: deeper than any other free tool, free as in actually free, and purpose-built so every feature maps to a real subtitling problem rather than a video-editor afterthought.
For κ araoke-style timing or complex typesetting against video — think match-the-sign, styled episode titles, or lyric animations — nothing on Mac at any price beats it.
What are the best Aegisub alternatives?
If Aegisub's complexity puts you off, the best alternatives depend on your goal. Jubler is simpler and cross-platform if you only need basic .srt timing. DaVinci Resolve includes a capable subtitle track if you're already editing there. Subtitle Edit is the closest Windows equivalent and runs under Wine in a pinch. For purely online work, Kapwing and Clideo handle simple caption jobs without installing anything. None of them match Aegisub's typesetting depth for .ass output.
