The legal notes at https://www.ycombinator.com/legal/#tou say "By uploading any User Content you hereby grant and will grant Y Combinator and its affiliated companies a nonexclusive, worldwide, royalty free, fully paid up, transferable, sublicensable, perpetual, irrevocable license to copy, display, upload, perform, distribute, store, modify and otherwise use your User Content for any Y Combinator-related purpose in any form, medium or technology now known or later developed. " .

If you do not wish your User Content to be displayed, I recommend that you do not upload it to the site.

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