AI Subtitle Annotator
Fast. Private. Perfect.
Add pinyin, furigana, or romaji reading aids to your Chinese and Japanese subtitles. Perfect for language learners. AI-powered with your own API key.
Drag & drop your subtitle file here
or click to browse
SRT, VTT, ASS, SSA, LRC, SBV, TTML, SCC, STL, SMI, TXT
How It Works
Select your Chinese or Japanese subtitle file.
Enter your OpenAI API key (get one at platform.openai.com).
Choose the annotation mode: Pinyin for Chinese, Furigana or Romaji for Japanese.
Select whether readings appear above the text or inline in parentheses.
Click Annotate. The AI processes subtitle text in batches to add reading aids.
Download the annotated subtitle file in your chosen format.
Why Choose AllSubConverter?
Your Privacy Matters
Everything runs in your browser. Your files are never uploaded.
Lightning Fast
Optimized processing engine converts files in seconds.
Truly Unlimited
No file size limits. No daily limits. Completely free.
Works Everywhere
Works on Windows, Mac, Linux, iOS, Android - any modern browser.
Key Features
Common Use Cases
Language Learning
Add pinyin to Chinese drama subtitles or furigana to anime subtitles for reading practice.
Karaoke Preparation
Add romaji to Japanese song subtitles so non-readers can sing along phonetically.
Study Materials
Create annotated subtitle files for language class materials or self-study.
Reading Support
Help learners who can speak but not read CJK characters by providing pronunciation guides.
Translation Review
Add readings to verify that subtitles match the spoken audio in tone and pronunciation.
Accessibility
Provide phonetic reading aids for viewers who are learning the language of the subtitles.
Frequently Asked Questions
Yes. This tool uses your own OpenAI API key to generate annotations. You can get one at platform.openai.com. The key stays in your browser and is sent directly to OpenAI, never to our servers.
The AI uses context to determine correct readings, which handles most cases well. However, Chinese has many homophones and Japanese kanji has multiple readings, so some annotations may need manual review for uncommon proper nouns or rare characters.
Above Text places the reading on a separate line above the original text (original line first, then reading line). Inline places the reading in parentheses after each word or character segment.
Pinyin is the romanization system for Mandarin Chinese (e.g. ni3 hao3). Furigana are small hiragana characters placed above kanji to indicate pronunciation. Romaji is the romanization of Japanese text (e.g. konnichiwa).
The tool is designed for Chinese and Japanese text. For Korean, you could use romaji mode, but accuracy may vary. English and other Latin-script text is passed through unchanged.
Input: SRT, VTT, ASS, SSA, LRC, SBV, TTML, SCC, STL, SMI. Output: SRT, VTT, or TXT (plain text with annotations only).