Dual Subtitles & AI Translation - InterSub Firefox

Dual Subtitles & AI Translation - InterSub

By: InterSub Add-on
Language learning with dual subtitle translator dualsub to immersive translate meaning of words: Spanish to English, to Japanese etc

Overview

Firefox Add-ons Store
Daily users
1,341 ▼ 4
Data as of 2026-07-26
Rating:
3.85
(20)
Version:
4.48.0
Last updated: 2026-07-01
Download
Ranking
#2,802 ▲ 2
Overall
Category rank
#109
Language Support

Features & Capabilities

InterSub turns every video into a language classroom. This Chrome extension delivers dual subtitles with real-time AI translation, hover word meanings, and an integrated AI Language Buddy to explain slang, grammar, and usage without leaving the screen. It works across popular streaming sites and platforms, making content more accessible and engaging for learners.

Key capabilities include instant translations across multiple languages, auto-generated captions when tracks are missing, vocabulary saving with AnkiDroid sync and Excel export, RTL language support, and flexible pricing. With support for 30+ languages and platforms like Netflix, YouTube, Prime Video, Crunchyroll, and Coursera, InterSub helps learners at all levels turn viewing into active study.

User Growth & Download Statistics

Manifest V3 Add-on Education AI Developer Tools
By:
InterSub
Daily users:
1,341 -4
Rating:
3.85
(20)
Version:
4.48.0 Last updated: 2026-07-01
Version code:
6332820
Creation date:
2023-12-22
Risk:
Very high risk impact Moderate risk likelihood
Permissions:
Host permissions:
  • <all_urls>
Content scripts matches:
  • *
  • *.newplayjj.com
  • *.thealloha.club
  • *.pljjalgo.online
  • *.allarknow.online
  • *.online-serial.com
  • *.algonoew.online
  • *.stloadi.live
  • *.lordfilm64.com
  • *.primevideo.com
    • See more
Size:
2.48MB
Email:
su*****@intersub.cc
URLs:
Website ,Privacy policy
Full description:
See detailed description
Source:
Firefox Add-ons Store
Data ingested on:
2026-07-26
Compare stats and ranking:

Ranking

# 2,802 ▲ 2
Other rankings
Upgrade to see more rankings

Other platforms

Chrome
Dual Subtitles & AI Translation - InterSub (v4.48.0)
20,000 4.57 (218)
Edge
Dual Subtitles & AI Translation - InterSub (v4.48.0)
21,841 4.90 (97)

For Developers

Monetize with App Pass Boost with Extension Booster

Contact the developer

Chrome-Stats does not own this Firefox add-on. Please use these information below to contact the Firefox add-on developer.
Developed by:
InterSub
Firefox Add-ons Store
https://addons.mozilla.org/firefox/addon/intersub/
Email:
su*****@intersub.cc
Website:
https://discord.gg/nCeeFuwjqB

Permission Change History

2025-09-15: Version 4.25.0 → 4.27.0
Add Host permissions: <all_urls>
Add Permissions: identity
Remove Permissions: <all_urls> https://app.intersub.cc/*
2025-08-21: Version 4.23.0 → 4.25.0
Add Permissions: webRequest <all_urls>
Remove Permissions: https://analytics.google.com/* https://hls.ted.com/* https://*.nflxvideo.net/* https://*.2sub.net/* https://*.2sub.movie/* https://*.2sub.pro/* https://*.voidboost.com/* https://*.pv-cdn.net/* https://*.udemycdn.com/* https://cr-play-service.prd.crunchyrollsvc.com/* https://*.ororo-mirror.tv/* https://*.crunchyroll.com/* https://api-edge.cognitive.microsofttranslator.com/* https://edge.microsoft.com/* https://translate.googleapis.com/* https://translate.google.com/*
2025-05-27: Version 4.13.0 → 4.15.0
Add Permissions: https://app.intersub.cc/*
Remove Permissions: https://*.intersub.cc/*
2025-05-08: Version 4.10.0 → 4.12.0
Add Permissions: https://*.2sub.net/*
2025-02-17: Version 3.105.0 → 3.109.0
Add Permissions: unlimitedStorage https://api-edge.cognitive.microsofttranslator.com/* https://edge.microsoft.com/* https://translate.googleapis.com/* https://translate.google.com/*
2024-12-14: Version 3.92.0 → 3.94.0
Add Permissions: https://*.crunchyroll.com/*
2024-12-08: Version 3.91.0 → 3.92.0
Add Permissions: https://*.ororo-mirror.tv/*
2024-12-02: Version 3.87.0 → 3.88.0
Add Permissions: https://*.2sub.pro/*
2024-11-21: Version 3.82.0 → 3.87.0
Add Permissions: https://cr-play-service.prd.crunchyrollsvc.com/*
2024-09-24: Version 3.67.0 → 3.70.0
Add Permissions: https://*.udemycdn.com/*
2024-04-01: Version 3.39.0 → 3.41.0
Add Permissions: https://*.pv-cdn.net/*
2024-03-21: Version 3.33.0 → 3.38.0
Add Permissions: https://*.intersub.cc/* https://*.2sub.movie/* https://*.voidboost.com/*
Remove Permissions: https://app.intersub.cc/*
2024-02-07: Version 3.22.0 → 3.29.0
Remove Permissions: scripting
2024-01-22: Version 3.20.0 → 3.22.0
Add Permissions: https://hls.ted.com/* https://*.nflxvideo.net/*

User Reviews

Users like the add-on for broad site support and helpful dual subtitles with translations, especially for language learning. However, recurring issues include unreliable subtitle loading, inconsistent performance across videos and platforms, onboarding friction due to credit-card requirements, incomplete support on some services (like Amazon Prime), and limited customization with some UI/navigation quirks.
Pros
  • Broad compatibility across sites (works on Netflix, YouTube, HBO Max and others).
  • Dual subtitles with translations and automatic translation features.
  • Helpful for language learning, especially English.
  • Customizable subtitle behavior and settings.
  • Enhances viewing of original-language content.
Cons
  • Subtitles sometimes fail to load or translate, reducing usefulness.
  • Reliability is inconsistent and the extension can stop working across videos.
  • Dashboard access requires entering credit card information, which deters usage.
  • Not all advertised platforms work (e.g., Amazon Prime) and some site support is incomplete.
  • Limited customization options (fonts/backgrounds) and navigation quirks (arrow-key controls, auto-pause).
Recent reviews
Все працює, рекомендую. Особливо сподобався ШІ переклад на українську мову з англійської. Everything works, I recommend it. I especially liked the AI ​​translation into Ukrainian from English.
by Le*****, 2026-05-03
I think this is the best extension to learning language in firefox.
by Fi*****, 2026-04-17
View all user reviews ›

Is Dual Subtitles & AI Translation - InterSub Safe?

Risk impact
Risk impact measures the level of extra permissions an extension has access to. A low risk impact extension cannot do much harms, whereas a high risk impact extension can do a lot of damage like stealing your password, bypassing your security settings, and accessing your personal data. High risk impact extensions are not necessarily malicious. However, if they do turn malicious, they can be very harmful.

Dual Subtitles & AI Translation - InterSub requires a lot of sensitive permissions. Exercise caution before installing.

Risk impact analysis details
  • Critical Allows access to all websites, posing a significant security risk as it can monitor and modify data from any visited site.
  • Critical ******* ****** ** *** ********* ******** ************** *************** **************** ***************** ****************** **************** ************* *************** *************** *********** ****** ********** ****** ************ ************* **************** ************** ************ ************* ***************** ******** ************ ****** ********** ********* ************** ************* ************* ************* ************* ************* *********** ************** *********** ******** ********** ********* ************ ********* ********* *********** ********* ********** ************ ********
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  • High ******* ******* **** *** ****** ***** *** ***** ** ******* **** ********* ********* ** * *********** *****
Risk likelihood
Risk likelihood measures the probability that a Firefox add-on may turn malicious. This is determined by the publisher and the Firefox add-on reputation on Firefox Add-ons Store, the amount of time the Firefox add-on has been around, and other signals about the Firefox add-on. Our algorithms are not perfect, and are subject to change as we discover new ways to detect malicious extensions. We recommend that you always exercise caution when installing a Firefox add-on.

Dual Subtitles & AI Translation - InterSub is probably trust-worthy. Prefer other publishers if available. Exercise caution when installing this add-on.

Risk likelihood analysis details
  • High This extension was recently updated in the past month. New updates may not be stable or safe.
  • High **** ********* *** *** **** ****** ********* ********** *** *** ** ****** ** *****
  • Low **** ********* *** ***** **** **** * ****** **** ***** ********** *** **** ****** ** ** ****** *** *****
  • Good **** ********* *** **** **** *******
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