unDraw

/license

Read below for the actual license but the gist is that you can use the 
illustrations in any project, commercial or personal without attribution or 
any costs. Just don’t try to replicate unDraw, redistribute in packs the 
illustrations or create integrations for it.
a rule of thumb (tldr)

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

full license text

Copyright 2024 Katerina Limpitsouni

All images, assets and vectors published on unDraw 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.

More precisely, unDraw grants you an nonexclusive, worldwide copyright license 
to download, copy, modify, distribute, perform, and use the assets 
provided from unDraw for free, including for commercial purposes, without 
permission from or attributing the creator or unDraw. This license does not 
include the right to compile assets, vectors or images from unDraw 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 or download the assets included on the 
website 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, 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.

A copy can be found at https://undraw.co/license