Frequently Asked Questions

SubFlow is an AI-powered subtitle translator that uses large language models (LLMs) to provide context-aware translations. Unlike traditional tools that translate line by line using Google Translate, SubFlow analyzes the full context of each scene to deliver natural, accurate translations that preserve idioms, cultural references, and character voice. Simply upload your SRT or VTT file, select your target language, and get professional-quality translations in seconds.

SubFlow supports all major subtitle formats: SRT (SubRip), VTT (WebVTT), ASS (Advanced SubStation Alpha), SUB (MicroDVD), and SBV (YouTube). You can upload any of these formats and download the translated result in the same format, or convert between formats using our built-in converter. SRT and VTT are the most commonly used formats and cover the vast majority of use cases.

Translating an SRT file with SubFlow takes three simple steps: 1) Upload your SRT file by dragging and dropping it onto the upload area or clicking to browse. 2) Select your target language — SubFlow auto-detects the source language. 3) Click Translate and wait for the AI to process your file. Once complete, you can review and edit the translation in the built-in editor, then download the translated SRT file. The entire process typically takes under 30 seconds for a standard one-hour movie subtitle file.

Yes! SubFlow offers a generous free tier that includes 15,000 lines of translation per month — enough for roughly 15 standard subtitle files. The free tier includes AI-powered translation, the built-in editor, format conversion, and no ads. If you need more capacity, batch translation, or browser extension features, our Pro plan starts at $9.90/month with unlimited translations.

Yes! SubFlow can generate bilingual subtitles that display both the original text and the translation. This is perfect for language learners who want to see both languages side by side. When exporting your translation, simply select the "Bilingual" format option. The output file will contain the original text on the first line and the translation on the second line, both aligned to the same timestamp. This format works with VLC, PotPlayer, YouTube, and most other players.

The SubFlow browser extension automatically detects videos playing on websites like YouTube, Vimeo, and others. It reads the existing subtitle track, sends it to our AI translation engine, and overlays the translated subtitles on top of the video in real time. The extension pre-translates all subtitles before playback begins, so there is zero delay during viewing. You can customize the display language, font size, position, and switch between single-language and bilingual mode.

SubFlow currently supports 18+ languages including English, Spanish, Portuguese, French, German, Chinese (Simplified and Traditional), Japanese, Korean, Arabic, Italian, Russian, Hindi, Thai, Vietnamese, Indonesian, Turkish, and Polish. You can translate between any combination of these languages. Our AI engine is particularly strong with major language pairs like English to Spanish, English to Chinese, and English to Japanese.

Yes, SubFlow preserves all original timing information exactly as it appears in the source file. Each subtitle cue keeps its original start time, end time, and duration. Our translation engine only translates the text content — it never modifies the timestamps. This ensures that the translated subtitles remain perfectly synchronized with the video.

SubFlow's AI translation achieves significantly higher accuracy than traditional machine translation tools like Google Translate. In our testing, users rate SubFlow translations 4 out of 5 on average, compared to 3 out of 5 for Google Translate. The key difference is context awareness — our AI considers surrounding lines, dialogue flow, and scene context rather than translating each line in isolation. This results in more natural phrasing, correct idiom translations, and consistent character names throughout the file.

SRT (SubRip) is the most universal subtitle format, supported by virtually every media player. It uses a simple structure: sequence number, timestamp range, and text. VTT (WebVTT) is the web standard format designed for HTML5 video. It supports additional features like styling, positioning, and metadata. For most users, SRT is the safest choice for compatibility. If you're embedding subtitles in a website or web player, VTT is preferred. SubFlow can convert between both formats instantly.

Yes, there are two ways: 1) Download the subtitle file from YouTube (or use a third-party tool), then upload it to SubFlow for translation. 2) Install the SubFlow browser extension, which can directly read YouTube's subtitle data and overlay translations in real time without downloading anything. The extension approach is the fastest — just install it, set your target language, and the translated subtitles appear automatically when you play a YouTube video.

Free users can upload files up to 2MB each, which is more than enough for standard subtitle files (a typical 2-hour movie SRT is around 100-200KB). Pro users can upload files up to 20MB each and batch-translate up to 50 files at once. Business users get 50MB per file and up to 100 files per batch. There are no practical limits on the number of subtitle lines — our engine handles files with thousands of lines efficiently.