UserFinder - will check more than 300 social media sites. 
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2Dimensions, 3dnews, 7Cups, 9GAG, About.me, Academia.edu, Airbit, Airliners, Alik.cz, AllMyLinks, Anilist, Apple Developer, Apple Discussions, Archive.org, Arduino, ArtStation, Asciinema, Ask Fedora, AskFM, Atom Discussions, Audiojungle, Autofrage, Avizo, BLIP.fm, BOOTH, Bandcamp, Bazar.cz, Behance, Bezuzyteczna, Bikemap, BinarySearch, BioHacking, BitBucket, BitCoinForum, Bitwarden Forum, Blogger, BodyBuilding, BongaCams, Bookcrossing, BraveCommunity, BuyMeACoffee, BuzzFeed, CNET, CapFriendly, Carbonmade, Career.habr, Championat, Change.org, Chatujme.cz, ChaturBate, Chess, CloudflareCommunity, Clozemaster, Clubhouse, Codecademy, Codechef, Codeforces, Codepen, Codewars, Coil, ColourLovers, Contently, Coroflot, Countable, DailyMotion, DeviantART, Discogs, Discuss.Elastic.co, Disqus, Docker Hub, Dribbble, Duolingo, Ello, Envato Forum, Etsy, Euw, EyeEm, F3.cool, Facebook, Fameswap, FanCentro, Fandom, Figma, Finanzfrage, Fiverr, Flickr, Flightradar24, Flipboard, Football, FortniteTracker, Fosstodon, Freelance.habr, Freelancer, Freesound, G2G, GNOME VCS, Gab, GaiaOnline, Gam1ng, Gamespot, Genius (Artists), Genius (Users), Gesundheitsfrage, GetMyUni, Ghost, Giphy, GitBook, GitHub, GitHub Support Community, GitLab, Gitee, GoodReads, Gradle, Grailed, Gravatar, Gumroad, GunsAndAmmo, GuruShots, Gutefrage, HEXRPG, HackTheBox, Hackaday, HackerEarth, HackerNews, HackerOne, HackerRank, Houzz, HubPages, Hubski, ICQ, IFTTT, ImgUp.cz, Imgur, Instagram, Instructables, Ionic Forum, Issuu, Itch.io, Itemfix, Jellyfin Weblate, Jimdo, Joplin Forum, KEAKR, Kaggle, Keybase, Kik, Kongregate, LOR, Launchpad, LeetCode, LessWrong, Letterboxd, Lichess, Linktree, Listed, LiveJournal, Lobsters, Lolchess, LottieFiles, Mapify, Medium, Memrise, Minecraft, MixCloud, Motorradfrage, Munzee, MyAnimeList, MyMiniFactory, Myspace, NICommunityForum, NationStates Nation, NationStates Region, Naver, Needrom, Newgrounds, Nextcloud Forum, Nightbot, Ninja Kiwi, NotABug.org, Nyaa.si, OGUsers, OK, OnlyFans, OpenStreetMap, Opensource, Oracle Community, Otzovik, OurDJTalk, PCGamer, PCPartPicker, PSNProfiles.com, Packagist, Pastebin, Patreon, Periscope, Pinkbike, Pinterest, PlayStore, Pokemon Showdown, Polarsteps, Polygon, Polymart, Pornhub, ProductHunt, PromoDJ, PyPi, Quizlet, Raidforums, Rajce.net, Rate Your Music, Rclone Forum, Redbubble, Reddit, Reisefrage, Replit.com, ResearchGate, ReverbNation, Roblox, RoyalCams, RubyGems, RuneScape, SWAPD, Sbazar.cz, Scratch, Scribd, ShitpostBot5000, Shpock, Signal, Slack, Slant, Slashdot, SlideShare, Smashcast, Smule, Snapchat, SoundCloud, SourceForge, SoylentNews, Speedrun.com, Splice, Splits.io, Sporcle, Sportlerfrage, SportsRU, Spotify, Star Citizen, Steam, SteamGroup, Strava, SublimeForum, TETR.IO, TLDR Legal, TRAKTRAIN, Telegram, Tellonym.me, Tenor, ThemeForest, TikTok, Tinder, TradingView, Trakt, TrashboxRU, Trello, TryHackMe, Twitch, Twitter, Typeracer, Ultimate-Guitar, Unsplash, VK, VSCO, Velomania, Venmo, Vero, Vimeo, Virgool, VirusTotal, WICG Forum, Warrior Forum, Wattpad, We Heart It, WebNode, Weblate, Whonix Forum, Wikidot, Wikipedia, Windy, Wix, WordPress, WordPressOrg, Wordnik, Wykop, Xbox Gamertag, Xvideos, YouNow, YouPic, YouPorn, Zhihu, akniga, aminoapp, authorSTREAM, babyRU, babyblogRU, chaos.social, couchsurfing, d3RU, dailykos, datingRU, devRant, drive2, eBay.com, eBay.de, eGPU, eintracht, fixya, fl, forum_guns, forumhouseRU, geocaching, gfycat, habr, hackster, hunting, iMGSRC.RU, igromania, interpals, irecommend, jbzd.com.pl, jeuxvideo, kofi, koo, kwork, labpentestit, last.fm, leasehackr, livelib, mastodon.cloud, mastodon.social, mastodon.technology, mastodon.xyz, mercadolivre, metacritic, minds, moikrug, mstdn.io, nairaland.com, nnRU, note, npm, opennet, osu!, phpRU, pikabu, pr0gramm, prog.hu, radio_echo_msk, satsisRU, skyrock, social.tchncs.de, spletnik, svidbook, toster, uid, wiki.vg, xHamster, znanylekarz.pl, zoomit