Resources

Niconico

Deleted Video Data
Video data for deleted videos (use with Wayback Machine)
Nicolog.jp
More helpful tool for getting video dates (almost always works)
Thumbnail Finder
Tool developed by Soma to attempt to get thumbnails from the wayback machine
Public Mylist Viewer
View public mylists for a video (requires Japan IP/VPN)

Bilibili

BiliPlus
Bilibili scraper that can be used to revive broken videos - tutorial available on Vocalost Discord server
Vocaloid Archive
Partial Bilibili archive focused on Vocaloid content

YouTube

Youtube Metadata finder
Website which attempts to provide metadata about Youtube videos (also has a search function)
YouTube Thumbnail Extractor
Extract thumbnails from YouTube videos
2009-2010 Metadata Archive
YouTube metadata from 2009-2010 period
Crav-ing Downloader
Video downloader (also works with Niconico)
Quite a Playlist
Get information for deleted/private videos in playlists
Cobalt Tools
Reliable video and audio downloader
Deleted Video Searcher
Automatic search tool for deleted YouTube videos
Thumbnail Finder Revived
Alternative thumbnail extraction tool
Unlisted Videos Archive
User-submitted collection of unlisted videos

Youku & Tudou

Pre-2008 Youku+Tudou Metadata
Youku & Tudou video metadata from before 2008
2008-15 Youku Metadata
2008-2015 Tudou Metadata
Tudou metadata from 2008-2015 (transferred to Youku)
2008-2015 Youku+Tudou Metadata
Youku+Tudou metadata archive from 2008 to mid-2015 (incomplete)
2007+2015-19 youku metadata
Youku Video Report System
Click "其他" and type "视频无法播放或损坏" to revive broken videos

Sina

Kugou

VocaRank Channels

All Vocaloid ranking channels have been moved to their own dedicated page for simplicity.