Key-Value databases

The in-memory data structure server that became the default cache, now with search, JSON and vectors built in.

AWS's serverless key-value and document store with single-digit-millisecond reads at any scale.

The Linux Foundation's BSD-licensed fork of Redis, now the default engine on AWS and Google Cloud.

The original multi-threaded, dead-simple distributed memory cache for key-value blobs.

Meta's embeddable LSM-tree key-value engine, the storage layer under dozens of databases.

Flash-optimized distributed key-value and document database for predictable sub-millisecond latency at scale.

Tiny memory-mapped B+tree with ACID transactions and lock-free readers; reached 1.0 in 2026.

The key-value store built into HashiCorp Consul for service config, locks and discovery.

Apple's ordered, strictly serializable distributed key-value store, built to have layers on top.

A Java in-memory data grid and stream processor that embeds in your app or runs as a cluster.

Google's original small, fast LSM key-value library, now in limited-maintenance mode.

Raft-based, strongly consistent key-value store that holds Kubernetes' cluster state.

The browser's built-in transactional object store, and the storage layer under most web local-first libraries.

AWS's managed Valkey, Redis OSS and Memcached service, provisioned or serverless.

Red Hat's open-source distributed cache and key-value store, embeddable or as a RESP-compatible server.

A distributed, memory-first SQL database and compute grid; Ignite 3 rebuilt it around Raft and Calcite.

In-memory database and Lua application server in one process, with an optional disk engine.

CNCF-graduated, Raft-replicated transactional key-value store in Rust; the storage layer of TiDB.

A multi-threaded, shared-nothing in-memory store that speaks Redis and Memcached on one big box.

MongoDB's default storage engine: MVCC B-tree with compression and snapshot isolation.

Serverless, per-request-priced Redis with an HTTP API built for edge and serverless functions.

Cheap, schemaless key-attribute store inside an Azure Storage account.

Embedded LSM storage engine that writes straight to object storage like S3.

Tiny reactive in-memory store for tables and values, with persisters and CRDT sync.

Erlang-based, Dynamo-style key-value store built to stay up through ugly failures.

The standard embedded JVM cache, with heap, off-heap and disk tiers and optional Terracotta clustering.

The 1990s-era embedded key-value library, now Oracle-owned, AGPL-licensed and rarely updated.

Oracle's long-running Java data grid, with a UPL-licensed Community Edition on GitHub.

AWS's original 2007 schemaless attribute store; still running but frozen in time.

Log-structured, embeddable key-value engine in pure Rust with keyspaces and transactions.

Pure-Rust embedded key-value store: copy-on-write B-trees, ACID, and a stable file format.

Oracle's sharded key-value and JSON store, available as Apache-licensed software or an OCI service.

Young C storage-engine library: transactional LSM with MVCC, column families and TTL.

Snap's multi-threaded Redis fork with active-active replication and FLASH storage, now dormant.

Ambitious lock-free embedded Rust database whose 1.0 rewrite has stalled in alpha.

Vercel's globally replicated read-optimized config store (renamed Global Config in 2026).

The open-source core of GemFire: a consistent, partitioned in-memory data grid for Java.

etcd's maintained fork of BoltDB: a simple, pure-Go B+tree store in a single file.

Pure-Go LSM key-value store that separates keys from values to cut write amplification.

A Redis-protocol database on RocksDB that trades a little latency for disk-sized capacity.

Lightweight pure-Dart key-value store for Flutter; development continues in the Hive CE fork.

Managed Valkey and serverless cache/pub-sub from ex-DynamoDB engineers, plus self-hosted Valkey tooling.

Off-heap, memory-mapped key-value store for Java with microsecond latency and cross-process sharing.

Microsoft Research's .NET cache-store that speaks RESP and scales across cores and storage tiers.

A native .NET distributed cache and data grid for Windows and Linux, with an Apache-licensed edition.

Embedded Java database exposing concurrent Maps, Sets and Queues backed by disk or off-heap memory.

Single-threaded stateful actors at the edge, each with its own strongly consistent SQLite store.

Tencent's mmap-backed key-value store for mobile apps, built as a faster SharedPreferences/NSUserDefaults.

Qihoo 360's Redis-compatible, RocksDB-backed store for datasets too big for memory.

Google Cloud's managed in-memory family: Valkey, Redis, Redis Cluster and Memcached.

Cockroach Labs' Go LSM engine, inspired by RocksDB and tuned for CockroachDB.

Client-side sync framework for instant web UIs; now free, open source and in maintenance mode.

Heavily reworked LMDB descendant: memory-mapped ACID B+tree with auto-growing files.

Broadcom's commercial in-memory data grid, the enterprise build of Apache Geode.

Globally cached, eventually consistent key-value store for read-heavy data at Cloudflare's edge.

Embedded, transactional key-value and JSON document engine in a single C file, with Jx9 scripting.

Embedded in-memory and hybrid database for devices, real-time systems and time-series analytics.

Embeddable in-memory key/value store for Go with ACID transactions, custom and spatial indexes, and TTLs.

Pure-Go embedded key-value store with Bitcask storage and Redis-like lists, sets and sorted sets.

D. J. Bernstein's constant database: immutable on-disk hash tables with two-read lookups and atomic swaps.

Boiler Bay's all-Java embedded B-tree database with a ConcurrentNavigableMap API and a server edition.

Redis-protocol NoSQL server that keeps strings, hashes, sorted sets and lists on disk in LevelDB.

ByteDance's RocksDB-compatible key-value engine built around Terark's searchable compression.

Netflix's memcached-based distributed cache with zone-aware replication, built for AWS microservices.

Netflix's Dynamo-style proxy layer that adds sharding and multi-datacenter replication to Redis and Memcached.

Couchbase's HB+-trie key-value storage library; no longer actively developed.

Simple Android key-value store that persists plain Java/Kotlin objects with Kryo; no SQL, no schemas.

A durable, Valkey/Redis-compatible in-memory database on AWS backed by a multi-AZ transaction log.

Embedded Go key-value store tuned for read-heavy workloads, using linear hashing and an mmap'd index.

Yahoo's embedded Java key-value store: off-heap index of every key plus append-only data files.

Yahoo's memory-mapped, zero-copy key-value library, a heavily tuned descendant of SGI's DBM.

Header-only C++11 append-only key-value store tuned for random reads on SSDs, built for the XRP Ledger.

Embeddable C datastore with 70+ Redis-like commands and a single-file ACID key-value store.

FAL Labs' C++ DBM library with hash and B+tree files; superseded by its author's Tkrzw.

Redis Ltd.'s own managed Redis on AWS, Azure and GCP, with Active-Active geo-replication and tiering.

Tiny embeddable C string key-value database from the radare2 project, built on djb's cdb format.

Hosted key-value store driven by plain HTTP calls, with scoped access tokens, TTLs and Lua bucket scripts.

Embeddable persistent and in-memory key-value engine for the JVM with typed Scala and Java APIs.

Single-file encrypted key-value store for secrets, with GPG or AES-256 and S3/SSH/gist sync.

Tongue-in-cheek but working C/Go key-value store: mmap hash table, LZ4, splay-tree cursors and a REST API.

Memory-mapped constant database: a faster, thread-safe, >4 GB rewrite of D. J. Bernstein's cdb.

A copyleft (LGPL) fork of Redis 7.2.4, now limited to security backports.

Small Java key/value API for JSON objects over LevelDB, RocksDB, LMDB or MySQL; abandoned in 2014.

Append-only image database in Go with a built-in HTTP API and Lua-scripted image processing; idle since 2018.

Microsoft's managed Redis built on Redis Enterprise, replacing the retiring Azure Cache for Redis.

Experimental lock-free in-memory MVCC key-value store for Go built on a Bw-tree; untouched since 2016.

Apache ActiveMQ Classic's built-in journal-plus-B-tree message store; a persistence engine, not a general DB.

Twitter's in-house, multi-tenant, eventually consistent key-value store with pluggable storage engines.

Distributed JCache and memcached-compatible key-value cache built into Caucho's Resin Pro app server.

Commercial in-memory data grid for .NET and Java with parallel query, Redis support and in-cache code.

IBM's Java in-memory data grid for caching, HTTP sessions and partitioned object storage; still patched.

Masterless wide-column database built for always-on writes across data centers.

C++ rewrite of Cassandra with shard-per-core design; also speaks the DynamoDB API.

Microsoft's globally distributed, multi-API NoSQL and vector database with SLA-backed latency.

Native multi-model database: documents, graphs, search and vectors behind one query language.

The original coordination service: hierarchical znodes, watches and ephemeral nodes for clusters.

Google's globally consistent, horizontally scaling SQL service with graph, vector and full-text built in.

Google's managed wide-column store, the original Bigtable, with HBase API and SQL access.

Rust multi-model database (documents, graph, vectors, live queries) that runs embedded, in WASM or clustered.

Early Java multi-model database mixing documents, graphs and objects, now in patch-only mode.

Memory-first distributed JSON database with SQL++, search, vector indexes and mobile sync.

Open-source distributed SQL from Yandex combining row and column tables, topics and vector search.

Hadoop's Bigtable clone: strongly consistent wide-column tables on top of HDFS.

Decentralised, offline-first graph database that syncs peer-to-peer in JavaScript.

Firebase's original JSON-tree database that syncs every change to connected clients in milliseconds.

Apple's iCloud record store for apps: private per-user data, a public database and built-in sync.

The most popular IndexedDB wrapper, with live queries and an optional Dexie Cloud sync service.

Transparent persistence for Python objects with ACID transactions and history.

Immutable, tamper-evident database with cryptographic proofs, offering key-value, SQL and document APIs.

Sorted, distributed key-value store on HDFS with cell-level security labels.

Immutable in-memory database with Datomic-style Datalog queries for Clojure, ClojureScript and JavaScript.

Multi-model Java database speaking SQL, Cypher, Gremlin, MongoDB and Redis protocols.

Confluent's SQL layer over Kafka Streams, still supported but superseded by Flink SQL for new work.

Multi-model data platform (SQL, objects, globals, vectors) with built-in interoperability, big in healthcare.

The Btrieve/Pervasive lineage: zero-admin embedded database with key-level and SQL access, now edge-focused.

Serverless Cassandra-as-a-service with vector search and a JSON Data API, now owned by IBM.

Shared-nothing, auto-sharded in-memory MySQL engine built for telecom-grade availability.

Toshiba's memory-first container database for IoT time series, with per-container ACID and SQL.

In-memory geospatial database and geofencing server that speaks the Redis protocol and HTTP.

Serverless peer-to-peer database on IPFS and libp2p using Merkle-CRDT logs.

Node.js runtime that fuses database, cache, app logic and MQTT/WebSocket messaging in one process.

Columnar streaming storage for Flink with primary-key tables and tiering into the lakehouse.

Tiny schema-less Rust search backend that returns object IDs, running in a few MB of RAM.

FIS's high-throughput M (MUMPS) database and compiler, behind major core-banking systems.

Open-source MUMPS/M hierarchical key-value database forked from GT.M, with SQL via Octo.

The commercial, enterprise-hardened distribution of Apache Ignite for low-latency SQL and compute.

Distributed columnar time-series database, now sold as Quasar, for tick, sensor and industrial data.

GigaSpaces' Java in-memory data grid with space-based processing, SQL queries and tiered storage.

Chinese distributed document database with native ACID storage, SQL instances and S3 API, used in many banks.

Lightweight Go graph database with GraphQL, an SQL-like query language, full-text search and scripting.

Embedded NoSQL document store for Java and Android with pluggable MVStore or RocksDB storage.

Serverless, CQL-compatible Cassandra service on AWS with no clusters to manage.

Converged C/C++ NoSQL platform mixing key-value, documents, time-series, stream processing, graph and ML.

Multi-model database for IoT and observability: time series, full-text, vector and key-value on Parquet.

Schema-less multi-model engine from Germany's Cortex AG, now sold as CortexEngine within Cortex-IP.

JVM-embeddable distributed SQL database replicated with Apache BookKeeper and ZooKeeper.

Ruby transactional document store that keeps every change as a commit in a Git repository.

Downloadable Spanner that runs on your own servers, other clouds or a laptop, with Paxos and auto-sharding.

Frank Denis's in-memory, persistent store for geographic points and key/value records with an HTTP/JSON API.

Keyed-file ISAM database plus SQL engine bundled with BASIS International's BBj Business BASIC platform.

FairCom's embeddable ISAM, SQL and JSON database engine, now sold as FairCom DB; roots in 1984's c-tree.

Couchbase's managed DBaaS: Couchbase Server clusters plus App Services sync and AI tooling.

Embedded transactional table-style document database for Java and .NET, including Android and Unity.