Before we started building Apollo Client, we actually tried Relay, but found it difficult to adopt, so we started a community effort to build a more flexible Gr

Before we started building Apollo Client, we actually tried Relay, but found it difficult to adopt, so we started a community effort to build a more flexible GraphQL client. Our main goals were to make incrementally adoptable, compatible with all view layers and easy to understand/debug. While Apollo is easier to adopt and use, it's still under active development, so it's not as stable as Relay, and hasn't been optimized for performance the way that Relay has. disclaimer: I work on Apollo Client