etcd vs SuperMassive

etcd is an open-source, strongly consistent distributed key-value store for data used by distributed systems and clusters of machines. It arranges values in hierarchical directories and lets clients watch keys or directories for changes. Clients can read and write values with standard HTTP tools such as curl, and keys may have optional time-to-live expiration. The project uses the Raft protocol and handles leader elections during network partitions, including when a leader machine fails. etcd is a core Kubernetes component and its primary datastore. The project provides pre-built binaries, source builds, and container images. Linux on AMD64 and ARM64 is tier 1; Darwin and Windows on either architecture are tier 3, and other platforms are unsupported. TLS and client-certificate authentication are supported for client and peer connections, but neither is enabled by default. The software is self-hosted and licensed under Apache 2.0, with a listed price of free. The integrations listing includes Kubernetes, CoreDNS, and language client libraries, while warning that third-party tools and libraries there are not tested or maintained by the etcd team.

SuperMassive is a self-hosted, open-source key-value database built for in-memory work, durability, and low latency. It spreads data across shards, and additional nodes can expand capacity horizontally. Writes rotate among primary nodes in sequence; reads run in parallel across primaries and, when needed, replicas. The project describes automatic failover and recovery when a node fails. Timestamp-based versioning settles conflicts in favor of the latest value. Commands include PUT, GET, DEL, INCR, DECR, REGX, STAT, RCNF, and PING. Nodes journal operations, while replicas copy any missing journal entries from their primary. Client connections use username-and-password authentication; nodes can use shared keys, and TLS is optional. Linux, macOS, and Windows builds are available as binaries or source, under the BSD-3-Clause license. The README identifies two limits: no transactions and only one user. GitHub marks the repository archived and read-only as of May 6, 2026.