ExtendDB is a DynamoDB-compatible database server that answers the DynamoDB wire protocol from your own infrastructure, so applications written for DynamoDB run unchanged against a database you operate. Any AWS SDK, the AWS CLI, or DynamoDB tooling points at the ExtendDB endpoint and keeps working: tables, items, Query and Scan with key conditions and filters, batch reads and writes, and transactions all behave as the SDK expects. Streams feed change data to your own consumers, TTL expires items on schedule, vector indexes add cosine, Euclidean, and dot product search to on-demand tables, and point-in-time export and import move data in and out. Storage is pluggable, with PostgreSQL as the reference backend, SQLite embedded for small installs, and MongoDB and Cassandra for teams already running them. Every request is SigV4-signed and evaluated by a built-in IAM-style engine with users, groups, roles, policies, permission boundaries, and access keys, and TLS is mandatory on every connection. A web management console administers accounts and credentials, and a JSON metrics endpoint reports DynamoDB-style CloudWatch metric names and dimensions. The server runs as a daemon or in the foreground under Docker, Kubernetes, or systemd, healthchecks without extra tooling, and keeps serving in air-gapped environments with no internet connection at all. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. Apache-2.0 licensed.