Ask HN: Who are the best companies for promoting open source?

My company is looking to create a policy to allow developers to have ownership of the technology they create, as long as it is non-competitive. For example, if a developer at Slack created a tool to do their job better (maybe a new IDE), they should have the freedom to open source it or sell it commercially.

This is tricky to implement which is why we'd like to gain inspiration from other companies who have done similar policies. Specifically, how do you deal with the same employee who works ~at~ Slack but spends most of their time working on their IDE?

To us it's ridiculous the amount of control some companies want of their employees. There is no reason a chat app should want ownership of an IDE that has nothing to do with their core business.

* I am not accusing Slack of being this way. I am just using them as an example.