Merge Subtitles
Combine subtitle files: overlay two languages, or join CD1 and CD2 into one file.
How it works
- 1
Drop your subtitle file into the box above.
- 2
Adjust the options; the preview updates instantly.
- 3
Download the result in the same or any other format.
Frequently asked questions
Is Merge Subtitles free?
Yes. Every tool on FastSub AI is free, with no sign-up, no watermark and no usage limits.
Are my files uploaded anywhere?
No. Your files are read and processed inside your browser tab. The only downloads are the app itself and, for AI tools, the model files.
Is there a file size limit?
Subtitle files up to 20 MB and videos up to several GB, limited only by your device's memory.
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