Relational Databases
PostgreSQL, MySQL, SQL Server, SQLite, Oracle DB
Distributed SQL / NewSQL
CockroachDB, YugabyteDB, TiDB, Google Cloud Spanner, Vitess
Document / NoSQL Databases
MongoDB, Amazon DynamoDB, Azure Cosmos DB, Couchbase, Firebase Firestore
Key-Value Stores & Caching
Redis, Memcached, etcd, Amazon ElastiCache, Azure Cache for Redis
Wide-Column Stores
Apache Cassandra, ScyllaDB, Google Bigtable, Apache HBase
Graph Databases
Neo4j, Amazon Neptune, ArangoDB, JanusGraph
Search Engines
Elasticsearch, OpenSearch, Apache Solr, Meilisearch, Algolia
Storage Engines
Encoding / Schema Evolution
Protocol Buffers, Apache Avro, Apache Thrift, Apache Parquet, Apache ORC, JSON Schema
Replication & Coordination
Apache ZooKeeper, etcd, HashiCorp Consul, Debezium
Message Queues & Event Streaming
Apache Kafka, Confluent, RabbitMQ, Apache Pulsar, NATS, Amazon SQS, Amazon SNS, Azure Service Bus, Azure Event Hubs, Google Cloud Pub/Sub
Batch Processing
Apache Hadoop, Apache Spark, AWS EMR, Azure Databricks, Google Cloud Dataflow, Apache Beam
Stream Processing
Apache Flink, Kafka Streams, Spark Structured Streaming, Apache Storm, Materialize, ksqlDB
Workflow Orchestration
Apache Airflow, Temporal, AWS Step Functions, Azure Durable Functions
Object / Blob Storage
Amazon S3, Azure Blob Storage, Google Cloud Storage, MinIO
Data Warehouses / OLAP
Snowflake, Google BigQuery, Amazon Redshift, ClickHouse, Azure Synapse Analytics
Container Orchestration & Service Mesh
Kubernetes, Docker, Istio, Envoy, Linkerd
API / RPC Layer
gRPC, GraphQL, Kong, Amazon API Gateway