This paper shows the performance and scalability evaluation of different blockchain platform implementations. Hyperledger Iroha implementing YAC consensus, Sawtooth implementing PoET algorithm, and Hyperledger Fabric framework implementation. Performance evaluation and scalability assessment were done by varying different sets of parameters such as block size, transaction sending rate, network traffic distribution, and network size. Performance evaluation was done based on average transaction latency, network throughput, and transaction failure rate. Scalability was assessed based on changes in transaction latency and throughput with increasing network size. Test results let to study the impact of a particular parameter on the private blockchain network performance and show how they can be adjusted to improve performance.