I've been perplexed for a while about this. It seems like many people are either unaware of how restrictive this license is, or are choosing to disregard it. For example, I find it hard to believe that all the projects leveraging MongoDB I see posted to HN are GPL-ing their code or buying a commercial license.<p>What am I missing? I sincerely don't understand.
Well at least for MongoDB the reason is quite clear. From their licensing page (<a href="http://www.mongodb.org/display/DOCS/Licensing" rel="nofollow">http://www.mongodb.org/display/DOCS/Licensing</a>):<p><pre><code> Note however that it is never required that applications using mongo be published.
The copyleft applies only to the mongod and mongos database programs. This is why
Mongo DB drivers are all licensed under an Apache license. Your application, even
though it talks to the database, is a separate program and “work”.</code></pre>