VoxSub by voxsub

VoxSub – Dual Subtitles, AI Translation & Subtitle Sync for Online Videos

VoxSub is an advanced subtitle toolkit for HTML5 video players. It helps you watch online videos with dual subtitles, translate and rewrite captions using AI, fix subtitle timing issues, search inside subtitle text, upload your own SRT files, customize subtitle appearance, and create smart subtitle profiles for better control while watching.

VoxSub is designed for language learners, anime viewers, foreign content, online courses, movies, and anyone who needs more control over subtitles on online videos.

VoxSub works with YouTube and many websites that use HTML5 video players, including video platforms, anime websites, course websites, and streaming-style players. On platforms where subtitles cannot be detected automatically, such as Netflix in some cases, you can upload your own SRT subtitle file and use VoxSub’s translation, synchronization, search, filtering, customization, and voice features normally.

Key Features

Dual Subtitles

Display two subtitle tracks at the same time.

You can watch with the original subtitle and a translated version together, such as English + Arabic, Japanese + English, German + Arabic, or any other supported language combination.

This is useful for language learning, comparing translations, understanding foreign content, and watching videos with more context.

AI Subtitle Translation & Rewriting

Translate subtitles using supported AI services.

You can translate subtitles into 20+ languages, simplify difficult text, rewrite subtitles in a different tone, adjust the style, or convert subtitles into supported dialects using your own custom instructions.

Examples of what you can do:

• Translate subtitles into another language
• Simplify complex sentences
• Rewrite subtitles in a casual or formal tone
• Convert subtitles into a supported dialect
• Improve subtitle readability
• Create a second subtitle track from the original one

AI features only run when you use them and may require your own API key depending on the selected AI service.

Upload Your Own SRT Files

If a video does not provide subtitles, or if VoxSub cannot automatically detect subtitles on a specific platform, you can upload your own SRT subtitle file.

After uploading a subtitle file, you can use VoxSub tools normally, including:

• Translation
• Rewriting
• Dual subtitles
• Timing sync
• Subtitle search
• Subtitle customization
• Filtering
• Smart profiles
• Optional voice dubbing

This makes VoxSub useful even on platforms where automatic subtitle extraction is not available.

Automatic Subtitle Detection

VoxSub can automatically detect available subtitles on supported HTML5 video players.

When subtitles are available and supported, VoxSub can extract and display them inside its own subtitle system, allowing you to translate, customize, search, sync, and manage them more easily.

Automatic detection depends on the website and the way the video player provides subtitles. Some platforms may require manual SRT upload instead.

Subtitle Timing Sync

Fix out-of-sync subtitles directly while watching videos.

VoxSub includes multiple timing tools to help you correct subtitle delay, subtitle drift, and timing problems without editing files manually.

Timing tools include:

• Global Offset
  Shift all subtitles forward or backward.
• Sync Here
  Match the current subtitle timing to the current playback position with one click.
• Two-Point Sync
  Correct subtitle drift across the entire video by syncing two different points.
• Precise Timing Controls
  Fine-tune subtitle timing quickly while watching.
• Reset Timing
  Restore the original subtitle timing anytime.

These tools are useful when subtitles are early, late, or slowly become out of sync during playback.

Subtitle Search

Search inside detected or uploaded subtitles.

You can search for a word or phrase and jump directly to the matching timestamp in the video.

This is useful for:

• Finding important moments
• Reviewing lessons or lectures
• Rewatching specific dialogue
• Studying vocabulary
• Navigating long videos faster

Smart Subtitle Profiles

Create custom subtitle profiles to control how subtitles behave.

Profiles can be used to replace words, hide or skip selected subtitle segments, mute selected audio parts, or apply custom rules while watching.

You can create separate profiles for different use cases, such as:

• Language learning
• Anime
• Movies
• Kids content
• Family-safe viewing
• Online courses
• Personal vocabulary rules

Subtitle rules and profile settings are stored locally in your browser. You can import and export them anytime.

Subtitle Customization

Customize how subtitles look and behave while watching.

VoxSub provides a simple control panel where you can adjust subtitle display options, including:

• Font size
• Subtitle color
• Subtitle position
• Background transparency
• Subtitle visibility
• Video/subtitle controls
• Quick access to search, timing, filtering, and subtitle tools

This gives you more control than the default subtitle options available on many websites.

Filtering Tools

Use subtitle filters and profiles to control specific words, phrases, or subtitle segments.

Depending on your profile rules, you can replace text, skip selected subtitle parts, or use subtitle-based filtering while watching.

This is useful for content control, studying, cleaning subtitles, or creating a more personalized viewing experience.

Optional AI Voice Dubbing

VoxSub includes optional AI voice playback features through supported AI voice services.

When configured with your own API key, VoxSub can generate voice playback from subtitle text using supported providers.

This feature is optional and only works when you set up the required service yourself.

Lightweight & Fast

VoxSub is built to stay compact, responsive, and efficient while watching videos.

The extension is designed to provide powerful subtitle tools without slowing down your browsing experience.

Privacy Friendly

VoxSub does not collect personal data.

Subtitle profiles, rules, timing settings, and customization settings are stored locally in your browser.

AI features only run when you trigger them. If you use an external AI service, subtitle text may be sent to the selected provider for processing according to that provider’s own terms and privacy policy.

VoxSub does not sell your data and does not track your personal browsing activity.

Supported Platforms

VoxSub works with YouTube and many websites that use HTML5 video players.

Supported or commonly used platforms include:

• YouTube
• Crunchyroll
• Dailymotion
• Vimeo
• Bilibili
• Udemy
• Anime streaming websites
• Course websites
• Many HTML5 video websites

For platforms where subtitles cannot be detected automatically, you can still upload your own SRT file and use VoxSub’s subtitle tools normally.

Browser Support

VoxSub is available for:

• Firefox
• Microsoft Edge

Who Is VoxSub For?

VoxSub is useful for:

• Language learners
• Anime viewers
• People watching foreign content
• Students watching online courses
• Users who need dual subtitles
• Users who need better subtitle timing tools
• Users who want to translate or rewrite subtitles
• Users who want to search inside subtitles
• Users who prefer uploading and controlling their own subtitle files

Why VoxSub Needs Permissions

VoxSub needs website access in order to detect HTML5 video players, read available subtitle tracks, display subtitles on top of videos, and apply subtitle tools while you are watching.

Download permission may be used for subtitle-related export or download features, such as saving processed subtitle files when needed.

VoxSub uses these permissions only to provide subtitle features. It does not collect personal data or track your browsing history.

Important Notes

Automatic subtitle detection depends on how each website provides its subtitles. Some websites expose subtitles in a supported way, while others may block or hide them.

If automatic subtitle detection is not available on a website, you can upload your own SRT subtitle file and continue using VoxSub’s tools normally.

Some AI features require configuration with your own API key from a supported AI provider.

VoxSub gives you full subtitle control while watching online videos — dual captions, AI translation, SRT upload, timing sync, search, customization, smart profiles, and optional voice tools in one extension.