We have made a commitment that [as much as possible of the platform will be open-source and publically available](https://topanswers.xyz/meta?q=1). Before releasing the code I'd like to get feedback on what license(s) to release it under.
Update: we have settled on the [AGPL v3](https://github.com/topanswers/topanswers/blob/master/LICENSE). We are free to revisit this decision in the future if need. Worth noting that the [Codidact](https://codidact.org/) project (which has similar aims to TopAnswers but will probably end up looking very different) [has also chosen AGPL](https://forum.codidact.org/t/what-software-license-should-we-use/205/29?u=jackdouglas) which may be useful if we share any code.
Especially given the history that led to this site existing in the first place and the way Q&A 'communities' work better when more people are involved in the same site rather than being fragmented all over the web, I would highly recommend a share-alike license of some kind. This means avoiding MIT and even BSD and Apache style licenses that do not have share-alike clauses. Anybody should be welcome to run and modify the code to their liking, but any modifications should be made available to others.
Starting a competing site with the same software should be an option, but the advantages of that site should be the people and community that chooses to use it not any technical superiority. Any technical advancements should be available to those that originally started or cantributed along the way.
The GPL is the pimary option that comes to mind, and the [Affero clause added in the AGPL in specific](https://www.gnu.org/licenses/why-affero-gpl.html) seems to suit these goals well, but there might be others that meet this goal too.