CaptionshaperFrequently asked questions
Is it really free?
Yes. No trial, no watermark, no limits. Captionshaper is open source, and you can support it on Ko-fi if it saves you time.
Does it upload my video?
No. Everything happens on your computer. The app downloads the speech model once (about 570 MB), and that's its only connection to the internet.
Which languages does it understand?
About 99, including English, Spanish, French, German, Portuguese, Russian, Chinese and Japanese. It detects the language for you. For less common languages, the Most accurate model makes fewer mistakes.
How accurate is it?
On clear speech it gets almost every word right. We test it on clips with known scripts in English, Spanish and German: 0.7% word error rate, with captions within 0.15 seconds of the voice. Noisy audio and strong accents make more mistakes, which is why fixing words is quick.
Can it translate?
It can turn speech in any supported language into English captions. Tick “Translate to English” before you start.
Is it fast on Windows?
It runs on the processor, about one to two times real time on a recent PC. On Apple Silicon Macs it uses the GPU and is around five times faster than real time.
Does it work on Intel Macs?
Not yet. The Mac version needs Apple Silicon (M1 or newer).
What can I export?
An MP4 video with the captions burned in, SRT subtitles (YouTube, Premiere, DaVinci Resolve, CapCut), VTT for websites, ASS with your full style, and a plain-text transcript.
Can I edit the captions?
Yes. Click any caption to edit it, use find and replace, split or merge captions, and undo anything. Words Captionshaper isn't sure about are underlined so you can check them first.
Does it work for TikTok, Reels and YouTube Shorts?
Yes. The Bold, Highlight, One word and Reveal styles are made for vertical video, and the phone view shows where each app puts its buttons so your captions stay clear of them.
Which files can I open?
Most video and audio files: MP4, MOV, MKV, WEBM, AVI, MP3, WAV, M4A and more, including iPhone videos.
How long can a video be?
There's no limit. A 10-minute video takes about two minutes on an Apple Silicon Mac. Longer videos simply take longer.
Why does my computer warn me when I first open it?
Captionshaper isn't signed with a paid Apple or Microsoft certificate yet, so both systems ask once. The download page shows how to open it, and you can check the file's checksum there.