&gt; Don&#x27;t most large organisations require something similar with their own open source projects? I know Google and Facebook do.<p>Mozilla gets by without one.  Apple&#x27;s approach for managing Swift, too.<p>&gt; It&#x27;s just a way of confirming that you own the rights to your contribution, and that you explicitly give Microsoft permission to use it.<p>If that&#x27;s all they wanted to do, they could get by with something resembling the terms that Mozilla gets its <i>committer&#x27;s</i> to sign.  Usually these CLAs are specifically written to go a lot further than that, though.  They usually take away a lot of the contributors&#x27; bargaining power.  Microsoft&#x27;s CLAs included.