Language Reactor records 1,878,769 monthly visits with +0.6% month-over-month growth and Freemium pricing. Sider records 2,644,740 monthly visits with -10.6% growth and Freemium pricing.
Learn languages from Netflix, YouTube, and real-world texts with dual subtitles and AI
AI sidebar and browser agent for reading, writing and research
| Dimension / Metric | ||
|---|---|---|
| Official Domain | languagereactor.com | sider.ai |
| Pricing Model | Freemium | Freemium |
| Monthly Visits | 1.88M (1,878,769) | 2.64M (2,644,740) |
| MoM Traffic Delta | +10.73K (+0.6%) | -314.2K (-10.6%) |
| Primary Market & Share | 🇺🇸 United States (13.3%) | 🇺🇸 United States (13.3%) |
| Direct Visits / mo | 1.45M | 1.7M |
| User Rating | 4.4 | 4.5 |
| Supported Platforms | Website | Website |
Learn languages from Netflix, YouTube, and real-world texts with dual subtitles and AI
View your target language together with a translation, pause, replay single lines, and jump back to the previous subtitle with a hotkey.
Hover or click any subtitle word to see definitions, part of speech, and pronunciation without leaving the video.
Automatically saves looked-up words and phrases, then quizzes you with the original context to build durable recall.
Bring the same translation and lookup workflow to ebooks, PDFs, articles, and other web pages.
AI sidebar and browser agent for reading, writing and research
A persistent panel that reads the page you are on and answers follow-ups with GPT, Claude or Gemini without copying content into another tab.
Summarise long articles, PDFs and YouTube videos, extract key points, and ask detailed questions about the source material.
Translate webpages, PDFs and images, compare bilingual output side by side, and have content read aloud for review on the move.
Delegate multi-step tasks across real websites — price comparison, form filling, research and inbox triage — using your existing logged-in sessions.
SpecialistOpenAI's flagship multimodal assistant powered by GPT-6 and GPT-5.6 for reasoning, coding, and deep research.
SpecialistOpenAI's flagship multimodal assistant powered by GPT-6 and GPT-5.6 for reasoning, coding, and deep research.
SpecialistAnthropic's frontier AI workspace powered by Claude 5.5 for agentic coding, analysis, and nuanced writing.
SpecialistAnthropic's frontier AI workspace powered by Claude 5.5 for agentic coding, analysis, and nuanced writing.
Offers a very similar browser sidebar experience with multiple AI models, but features slightly different pricing and workspace tools.
Offers a very similar browser sidebar experience with multiple AI models, but features slightly different pricing and workspace tools.
Provides powerful bilingual translation across streaming video and web pages, though less focused on dedicated flashcard workflows.
Provides powerful bilingual translation across streaming video and web pages, though less focused on dedicated flashcard workflows.
Provides robust browser-based summarization and prompt assistance, but lacks some of Sider's deeply integrated multi-model chat UI features.
Provides robust browser-based summarization and prompt assistance, but lacks some of Sider's deeply integrated multi-model chat UI features.
SpecialistLearn a new language by talking to lifelike AI tutors
SpecialistLearn a new language by talking to lifelike AI tutors
Excels at advanced web automation and data extraction alongside chat, but has a steeper learning curve than Sider.
Offers similar dual-subtitles and video translation for Netflix and YouTube, but with a more modern AI interface.
Offers similar dual-subtitles and video translation for Netflix and YouTube, but with a more modern AI interface.
SpecialistSpeak a new language from day one with human-like AI and expert human tutors
SpecialistSpeak a new language from day one with human-like AI and expert human tutors
Free / Open-sourceSummarize YouTube, Google, and any page with AI — free in your browser
Free / Open-sourceSummarize YouTube, Google, and any page with AI — free in your browser
Integrates bookmark management and content composition into a clean sidebar, but has a more limited feature set than Sider.
Integrates bookmark management and content composition into a clean sidebar, but has a more limited feature set than Sider.
Delivers streamlined inline writing and webpage summarization via a browser extension, but with fewer custom sidebar tools.
Delivers streamlined inline writing and webpage summarization via a browser extension, but with fewer custom sidebar tools.
