SRT Converter
FileFlip converts SRT files into 5 other formats entirely inside your browser, using FFmpeg compiled to WebAssembly. The SRT file is never uploaded to a server: it is read off your disk, converted on your own machine, and saved back by the browser. There is no file-size limit and no account to create.
How do I convert an SRT file?#
- Drop your SRT file onto the converter at the top of this page, or click it to pick one from your computer.
- Choose the format you want out of it. FileFlip downloads the engine that conversion needs, once, and your browser caches it.
- Conversion starts the moment you pick the format, and the result is yours to download. The work happens in this tab, so nothing is uploaded and nothing is queued.
Is it safe to convert SRT files online?#
Yes, because nothing is uploaded. FileFlip converts SRT files inside the browser tab you already have open, using WebAssembly builds of the same engines a desktop converter would install. Your file is read from your own disk into the page's memory, and no request carrying it is ever made.
You do not have to take that on trust. Open your browser's network panel, run a conversion, and you will see the engine come down and your file go nowhere. There is no upload, no server-side copy, no retention window, and no account tied to what you converted.
How FileFlip works lists every engine, its version and its download size, and shows how to check for yourself that nothing leaves your machine.
What happens to a SRT file#
FileFlip converts SRT into 5 formats with FFmpeg, all of it inside the browser tab. Each conversion below names the engine it uses, what it downloads, and exactly what that conversion keeps or drops.
| Category | Subtitles |
|---|---|
| File extension | .srt |
| FileFlip support | Read and written |
| Conversions available | 5 |
| Engines | FFmpeg |
| Downloaded to your browser | 30.8 MB on the first conversion, then cached |
What is an SRT file?#
An SRT file numbers each caption in order and gives it a start and end timecode measured in hours, minutes, seconds and milliseconds, with the line or lines of dialogue printed underneath and a blank line separating one caption from the next.
Use SRT when the file needs to open in the widest possible range of players and sites and doesn't need positioning or styling.
Convert away from SRT when the destination needs something SRT cannot hold, such as WebVTT's on-screen cue positioning or ASS's karaoke timing and typesetting.
The SRT file format reference covers the specification, the programs that open one, and what each conversion keeps or drops.
SRT questions people ask#
What program opens an SRT file?
An SRT file opens in essentially any video player, including VLC, and in dedicated subtitle editors like Subtitle Edit and Aegisub. Because it's plain text, it also opens in Notepad or TextEdit, though it will display raw timecodes rather than a preview.
Why does SRT have no styling or colors?
SRT was designed as a byproduct of ripping DVD subtitles to text, not as a typesetting format, so it only ever recorded a timecode and the caption line. That simplicity is why every player reads it; formats like ASS exist specifically to add styling back in.
Does an SRT file break if the video's frame rate changes?
No. SRT times each caption by clock time, in hours:minutes:seconds,milliseconds, so it stays in sync no matter what frame rate the video plays at. That's different from a frame-based format like MicroDVD SUB, which times captions by frame number and drifts out of sync if the frame rate doesn't match.
What's the difference between SRT and VTT?
SRT is plain numbered captions with no styling, while WebVTT is the W3C's version of the same idea built for HTML5 video, adding cue positioning and CSS-style formatting. The two are close enough that converting SRT to VTT is a near-lossless, mostly mechanical change.
Can I add bold or italic text to an SRT file?
Some players accept HTML-style tags like <b>, <i> and <font color> inside an SRT caption, but this was never standardized, so support varies by player and the tags are stripped or shown literally in others. A format built for styling, such as ASS, is the reliable way to control text appearance.