Modern assistants still forget everything when you close the tab unless something persists beyond the context window. Agent memory providers are services or libraries that hold facts and summaries across sessions — often wired in as plugins so the framework stays thin while memory scales. This guide compares eight backends that ship as Hermes Agent external memory plugins — Honcho, OpenViking, Mem0, Hindsight, Holographic, RetainDB, ByteRover, and Supermemory — and explains how they fit into broader AI systems stacks. The same vendors appear in OpenClaw and other agent tooling via community or official integrations. The AI Systems Memory hub lists this article alongside Cognee and related guides. For Hermes-specific bounded core memory (MEMORY.md and USER.md), freezing behaviour, and triggers, see Hermes Agent Memory System . Hermes Agent lists eight external memory provider plugins for persistent, cross-session knowledge. Only one external provider can be active at a time.…