Kafka vs Riak: What are the differences?
Kafka: Distributed, fault tolerant, high throughput pub-sub messaging system. Kafka is a distributed, partitioned, replicated commit log service. It provides the functionality of a messaging system, but with a unique design; Riak: A distributed, decentralized data storage system. Riak is a distributed database designed to deliver maximum data availability by distributing data across multiple servers. As long as your client can reach one Riak server, it should be able to write data. In most failure scenarios, the data you want to read should be available, although it may not be the most up-to-date version of that data.
Kafka belongs to "Message Queue" category of the tech stack, while Riak can be primarily classified under "Databases".
"High-throughput" is the primary reason why developers consider Kafka over the competitors, whereas "High Performance " was stated as the key factor in picking Riak.
Kafka and Riak are both open source tools. It seems that Kafka with 12.5K GitHub stars and 6.7K forks on GitHub has more adoption than Riak with 3.22K GitHub stars and 526 GitHub forks.
Uber Technologies, Spotify, and Coursera are some of the popular companies that use Kafka, whereas Riak is used by SendGrid, Sentry, and OpenX. Kafka has a broader approval, being mentioned in 501 company stacks & 451 developers stacks; compared to Riak, which is listed in 15 company stacks and 10 developer stacks.