kitio.aiAdded Oct 29, 2026
Line 21
PaidLive captions that mix human captioners with AI tools
What is Line 21?
Line 21 provides live captioning for events, streams and meetings, combining certified human captioners with automatic speech recognition. AI tools translate, proofread and add event context, and the output can be encoded into video streams.
Services include manual captioning, ASR, AI translations in over 120 languages, an AI proofreader that catches typos and name errors, and a context builder for each event. Captions can be sent over RTMP, encoded as CEA 608/708, streamed over HLS or embedded with a player.
Integrations include YouTube, Twitch, Facebook, Vimeo, Zoom and Microsoft Teams, and there is an API and a meeting bot. Prices are per hour of use, with pay-as-you-go billing or yearly plans with volume discounts.
Features
- Human and ASR live captioning
- AI translation
- AI proofreader
- RTMP and HLS streaming
- Meeting bot
- API
Tags
Releases
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Organization
Line 21
Listed by kitio.ai · unverified owner
Pricing
- Pricing model
- Paid
- Paid options from
- Not listed
Line 21 plans
Caption minutes
$3 / hour
- Only when you bring your own captioners
- Caption view page
Meetings
$6 / hour
- Speech-to-text and translation
- Diarization
- Dedicated meeting page
AI translations
$9 / hour
- 120+ languages
- Custom dictionaries
ASR
$15 / hour
- Speech-to-text models
- Custom dictionaries
- Audio or RTMP ingest
AI proofreader
$21 / hour
- Context-aware LLM checks
- Custom event context
Human captioners
From $120 / hour
- Certified professional writers
- On-site or remote
Prices in USD, checked Oct 29, 2026. Plans change often, so confirm on the Line 21 site.Official pricing
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Pros and cons
Pros
- Combines human and AI captioning
- Works with Zoom, Teams and streaming platforms
- Pay-as-you-go billing
Cons
- Human captioning starts at $120 an hour
- Prices are per service per hour
- Built mainly for events and broadcasts
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Q&A
What is Line 21?
Line 21 provides live captioning for events, streams and meetings, combining certified human captioners with automatic speech recognition. AI tools translate, proofread and add event context, and the output can be encoded into video streams.
Does Line 21 only use AI?
No. It offers human captioners, ASR and AI-assisted tools, so you can choose the mix for each event.
Which platforms can receive the captions?
The site lists YouTube, Twitch, Facebook, Vimeo, Zoom, Microsoft Teams and custom RTMP destinations.
How much does Line 21 cost?
Line 21 is paid.
Is there a free version of Line 21?
No. Line 21 is a paid tool.
What are the main features of Line 21?
Human and ASR live captioning, AI translation, AI proofreader, RTMP and HLS streaming, Meeting bot, API.
Who makes Line 21?
Line 21 is made by Line 21.
What are the best alternatives to Line 21?
Popular alternatives include Akkadu, Interpret AI, Whisper.