A simple rule of thumb (tldr)

If you are working on something and want to use unDraw Handcrafts artwork to improve its appearance, modified or not, without the need for attribution or cost, you are good to go. If you find unDraw Handcrafts or the contained artwork to be in the center of what you are doing (e.g. sell or re-distribute one/some of them, train an algorithm, add them in an app), then you should not proceed.

Full License

Copyright 2022 Katerina Limpitsouni

All images, assets and vectors published on unDraw Handcrafts can be used for free. You can use them for noncommercial and commercial purposes. You do not need to ask permission from or provide credit to the creator or unDraw or unDraw Handcrafts.

More precisely, unDraw Handcrafts grants you an nonexclusive, worldwide copyright license to download, copy, modify, distribute, perform, and use the assets provided from unDraw Handcrafts for free, including for commercial purposes, without permission from or attributing the creator or unDraw Handcrafts. This license does not include the right to compile or re-sell assets, vectors or images from unDraw Handcrafts to replicate a similar or competing service, in any form or distribute the assets in packs or otherwise. This extends to automated and non-automated ways to link, embed, scrape, search, use for generative AI training purposes or download the assets included on the website and integration without our consent.

Regarding brand logos that are included:

Are registered trademarks of their respected owners. Are included on a promotional basis and do not represent an association with unDraw or its users. Do not indicate any kind of endorsement of the trademark holder towards unDraw Handcrafts, nor vice versa. Are provided with the sole purpose to represent the actual brand/service/company that has registered the trademark and must not be used otherwise.