PostgreSQL vs. MySQL. MongoDB vs. Cassandra. Solr vs. Elasticsearch. ReactJS vs. AngularJS. If you have an open source project that you are passionate about, chances are a competing project exists and is doing similar things, with users as passionate as yours. Despite the "we're all happily sharing our code" vibe that many individuals in open source love to project, open source business, like any other, is filled with competition. Unlike other business models, however, open source presents unique challenges and opportunities when it comes to competition.