We believe human captioners can benefit from the recent advances in Ai technology. This is why we have built an entire platform around this Human + Ai collaboration, with features such as the Ai Proofreader and automated caption translations. These complement other traditional features such as captiong video encoding (CEA-608 / CEA-708).



Championing affordable accessibility, our comprehensive solution in the world of captioning and transcription services stands apart. We offer a suite of integrated features that converge into a single, streamlined experience for each user.

Our unique position in the market is not just in what we offer, but in how we offer it - affordably, efficiently, and without compromise.

AI Proofreader

Precision Meets Efficiency. Line 21's AI Proofreader guards against goofs - accurate and efficient, revolutionising the way captions are refined. Harness the power of AI to polish every line of text, ensuring quality accessibility, avoiding brand embarrassment, and that your audience only laughs at captions that are meant to have a punchline.

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Automatic Speech Recognition (ASR)

Advanced real-time speech-to-text conversion tool, using multiple AI speech recognition engines to support over 100 languages. Each engine is tailored with its unique glossary, enhancing accuracy and context understanding. The ASR system also offers automatic translation of captions into numerous languages, promoting global accessibility. This blend of technology ensures precise and efficient transcription, making spoken content more accessible and understandable for a diverse international audience.

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CEA Encoding

With Line 21, our minimal delay encoding is faster than other solutions, and better value per minute. Our software embraces both 608 and 708 protocols, offering unparalleled compatibility with any platform. Whether streaming online content or broadcasting over the airwaves, Line 21's ensures your captions are seamlessly integrated in any language, delivering a consistent viewer experience across all channels.

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Captions Display Styles

Accessibility is the heart of what we do. Line 21's captions are designed to support your audience wherever they are, offering flexibility in display options on any device. Choose between a straightforward browser link for immediate access or a downloadable subtitle overlay that complements your content.

Our fully customisable display options come with a built-in colour contrast checker to help you stay compliant, and your audience can alter the result to their individual preference.


Embark on a journey of global reach with Line 21's bespoke translation engines - connecting you with audiences around the world. Empowered by human writers, proofread and machine translated for a seamless result that maintains the original tone and context. Expand your horizons and engage with viewers, opening up an inclusive and accessible world.

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Download your live captions transcript at the end of each event in multiple formats and languages. Whether you want to review or repurpose your session’s text, this feature is always included as standard in each event.

File types available: .txt, .srt, .webvtt.