QuestDB is a high performance, open-source, time-series database

Apache Pulsar - distributed pub-sub messaging system

The world's fastest open query engine for sub-second analytics both on and off the data lakehouse. With the flexibility to support nearly any scenario, StarRocks provides best-in-class performance …

Micro second messaging that stores everything to disk

Ultra-fast matching engine written in Java based on LMAX Disruptor, Eclipse Collections, Real Logic Agrona, OpenHFT, LZ4 Java, and Adaptive Radix Trees.

EJBCA® – Open-source public key infrastructure (PKI) and certificate authority (CA) software.

XiPKI: Compact open source PKI (CA, OCSP responder, certificate protocols ACME, CMP, EST, SCEP), with full support of PQC MLDSA (Dilithium) and MLKEM (Kyber).

Kafka-on-Pulsar - A protocol handler that brings native Kafka protocol to Apache Pulsar

SignServer – Open source, PKI-based signing software to sign code, documents, timestamps and more.