Sideline — Danmaku & Comments for YouTube

YouTube comments, on screen.

YouTube comments, right where you’re watching. Sideline brings live chat, replay chat, and loaded timestamped comments into your video. Choose smooth scrolling danmaku, a movable and resizable chat box, or comments at the top or bottom. Choose the pace: Quiet groups repeated chat and remembers it for 60 seconds; Balanced groups five-second bursts; Lively keeps messages separate within display limits. Matching ignores case and symbols. Repeat counts update without restarting scrolling, and timestamped comments show available like counts. Scrolling follows video pause and playback speed. Four themes, four display styles, and ten interface languages. Adjust text size, opacity, speed, direction, and comment area. Click the leaf in YouTube’s player controls to get started. Optional automatic comment loading is off by default. No Sideline account, analytics, or comment uploads. Preferences stay in local extension storage; comments stay in memory for the video session. YouTube/Google may serve avatars and emoji. Optional on-device translation requires browser support and is unavailable in Firefox. About half of Sideline was vibe-coded with AI assistance. It’s open source, and all contributions are welcome: fixes, translations, design, and testing. https://github.com/RobinPourtaud/Sideline For desktop YouTube watch pages. Sideline shows comments YouTube has loaded; it does not scan all comments or include replies. Shorts, embeds, and mobile layouts are not supported. Screenshots use the actual interface with synthetic comments and an original demo scene. Independent project, not affiliated with YouTube, Google, Microsoft, or Mozilla. Support: sideline@pourtaud.dev