If not, would it be possible to open source it?
No, we haven’t open sourced Mojeek. SEO means that it is very difficult for a search engine to be completely open source; it would be open to manipulation from actors seeking to game the results ranking. Having said that we greatly appreciate, and benefit from, open-source initiatives such as cURL and Linux. So we would not discount open sourcing some of our code in the future; when and if we see an advantage in doing so. The determining factor is that such an initiative benefits both users and the business.