Websites I use for free svg Illustrations
https://undraw.co/illustrationsAn open-source illustrations website, where you can change the colors of the illustrations online before downloading.
https://www.manypixels.co/gallery/ManyPixels offer free svg illustrations with the possibility to customize the color as well.
https://illlustrations.co/100 beautiful illustrations, designed by Vijay Verma during a 100 days of illustrations challenge.
https://isometric.online/This website offers a searchable list of nice and free isometric illustrations.
https://www.glazestock.com/Glaze offers a lot of royalty-free high quality illustrations.
https://lukaszadam.com/illustrationsLukasz Adam is an independent web designer and offers a lot of free svg icon sets on his website.
https://www.humaaans.comHumaaans have a variety of different svgs of people. They also offer each element of the humans separately to be able to create your own.
https://woobro.design/Woobro has some very detailed high-quality svgs for some specific use cases.
https://fresh-folk.com/Similar to Humaaans, Fresh Folk offers people for self composing with a different style.
https://www.opendoodles.com/Open Doodles provide a bunch of illustrations in a sketchy style.
Please let me know if you have anything to add to that list :)
Edit (Suggestions from comments):
https://game-icons.net/ ( /u/Asmor )
https://pimpmydrawing.com/ ( /u/stoned_guerilla )
https://www.flaticon.com/ ( /u/lower-violins )
https://iconmonstr.com/ ( /r/Fireacaree )
https://konpa.github.io/devicon/ ( /r/DaCush )
https://icons8.com/icons/set/emoji ( /r/tomasvn )
By /r/FnnKnn :
https://www.karthiksrinivas.in/charco
https://www.veila.me/freebies/scandinavian-houses-free-vector-images
https://github.com/MariaLetta/mega-doodles-pack
https://www.isometriclove.com/