Line 21
PaidComprehensive real-time captioning solutions for all your accessibility needs.
About Line 21
Line 21 is a complete and highly flexible live captioning platform that supports both human and AI-powered solutions. It allows users to integrate accurate closed captions into live events—whether online streaming, in-venue, or broadcast. The platform offers a wide range of services including manual captioning, automatic speech recognition (ASR), AI Proofreader, AI translations in 120+ languages, RTMP/HLS streaming, caption encoding (CEA 608/708), embeddable player, meeting bot, and API access. Trusted by agencies and event organizers, it provides a modern software stack with 15+ integrations (YouTube, Twitch, Facebook, Vimeo, Zoom, Microsoft Teams, etc.) and 10+ AI models. Pay-as-you-go pricing with no plans means users only pay for minutes used, with per-hour rates for specific services.
Key Features
Pros & Cons
- Supports both human and AI captioning, allowing flexibility for accuracy vs. speed
- Wide language coverage with over 100 languages and 120+ for AI translations
- AI Proofreader with context-aware correction reduces errors in real-time
- Pay-as-you-go pricing with no plans or long-term commitments
- 15+ integrations with major streaming platforms and meeting tools
- Low-latency streaming and encoding (RTMP, HLS, CEA 608/708)
- Technical support available live during events
- Global network of professional captioners for high-accuracy needs
- Pricing per minute can add up for long or frequent events
- Dependence on internet connectivity for real-time captioning
- AI accuracy may vary with strong accents or poor audio quality
- Human captioner rates ($120/hr) may be expensive for budget-constrained users
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