Free online subtitle tools.
Subtitle processing, in your browser.
Convert, adjust and translate subtitle files — SRT, ASS, WebVTT, SBV, Blu-ray PGS (SUP) and VobSub. Files are parsed locally; translation sends subtitle text to Google after you choose to translate.
- No signup
- No queues
- No daily limit
- Free tools
- Local file processing
Pick your tool
How it works
- 1
Drop your file in
Drag and drop, or pick files from your device. Batch conversions welcome.
- 2
Tweak the settings
Pick formats, offsets and options — sensible defaults mean zero-config for most jobs.
- 3
Download the result
Files convert right in your browser and save straight back to your device.
Subtitle conversion
Convert between SRT, ASS, WebVTT and SBV, export plain text, or go the other way entirely: render text subtitles into Blu-ray PGS (SUP) picture subtitles, and turn PGS (SUP) or VobSub (IDX/SUB) picture subtitles back into editable text with OCR.
Everything — including subpicture rendering and OCR — happens locally in your browser. No files or content are ever sent to our server, so your material stays completely private.
Timing adjustment & cleanup
Subtitles out of sync? Apply timing shifts in three modes — simple (whole file), partial (a cue range) or linear (progressive drift) — and clean up common flaws in cue text while you're at it.
Like everything else on Subtitle One, adjustment is fully local: your files never leave your browser.
Subtitle translation
Translate subtitle text with a target language currently supported by Google Translate. The files are parsed in your browser, but the subtitle text is sent to Google when translation starts. Machine output can be wrong; review it before use.
Supported conversions
| From ↓ / To → | SRT | WebVTT | ASS / SSA | SBV | TXT | PGS (SUP) |
|---|---|---|---|---|---|---|
| SRT | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| ASS / SSA | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| WebVTT | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| SBV | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| PGS (SUP) | ✓ | ✓ | ✓ | ✓ | ✓ | — |
| VobSub IDX/SUB | ✓ | ✓ | ✓ | ✓ | ✓ | — |
Picture subtitles (PGS SUP, VobSub IDX/SUB) are converted to editable text with OCR — nothing can be rendered back into VobSub, and Blu-ray PGS (SUP) output needs a text source. Same-format jobs belong on the adjustment page.
Frequently asked questions
Are my subtitle files uploaded to your server?
Subtitle files are parsed in your browser and are not uploaded to our server. For translation, subtitle text is sent to Google Translate only after you explicitly start translation. Other site features such as ads, metrics, and access verification may make network requests.
Which subtitle formats are supported?
Text-based subtitles: SRT, ASS/SSA, WebVTT and SBV. Image-based subtitles: Blu-ray PGS (SUP) and VobSub (IDX/SUB). Text subtitles can be converted between all text formats or rendered into Blu-ray PGS (SUP), and image subtitles can be converted back to text via OCR.
Convert image subtitles with the SUP / PGS to SRT converter or the VobSub SUB/IDX to SRT converter.
Can I convert text subtitles to Blu-ray PGS (SUP)?
Yes. Text subtitles such as SRT, ASS and VTT can be rendered into Blu-ray PGS (SUP) picture subtitles. Each cue is drawn into a bitmap and encoded as a SUP stream locally in your browser — no files are ever sent to a server. Upload your files, choose "Blu-ray PGS (SUP)" as the output format, and click Convert.
Do I need to create an account?
No. There is no signup, no queue and no daily limit. Open a tool, drop your file in, and download the result.
Why does my CPU usage go so high during subpicture conversion?
Conversion runs entirely in your browser using your own CPU, and converting picture subtitles is CPU-intensive: every cue picture must be extracted, processed and recognised by the OCR engine, and a single file can contain thousands of cues. A faster processor means faster conversions.
Which browser works best?
Most modern browsers work, including mobile browsers. We develop mainly on Firefox and test on Chrome and Safari too — after recent optimisations, Chrome is currently the fastest browser for subpicture conversions.
More questions? Check the full FAQ or contact us.
Ready when you are.
Drop in a subtitle file and have it converted in seconds — free, private, no signup.
Convert a subtitle now