Letta handles agent lifecycle, memory, and execution in one platform. RetainDB handles memory, context, and knowledge base ingestion — and plugs into whatever you're already running. The question isn't just 'which memory is better' but 'do I want a platform or a layer that also handles my team's documents?'
Letta is a platform you build agents on. RetainDB is a library you drop into agents you already have. If you're adding memory to an existing product, RetainDB. If you're designing agents from scratch and want a full platform, Letta.
When teams evaluate Letta for user-memory use cases, the scope often expands: 'add memory to our agent' becomes 'migrate our agents to a new platform'. RetainDB is explicitly designed to avoid that. Three lines of SDK, any framework, no platform adoption required.
RetainDB publishes LongMemEval scores at retaindb.com/benchmark: 88% preference recall, 79% overall. Letta doesn't publish equivalent scores for its memory subsystem. For teams that need internal validation before shipping, that gap matters.
RetainDB adapters drop into Vercel AI SDK, LangChain, LangGraph, or plain REST. The wizard generates integration code for your existing setup. You're not adopting a new execution model — you're adding a memory layer to the one you have.
Letta handles memory within its platform execution model — not your help center docs, Notion workspace, or PDFs. RetainDB ingests all of it: 22 built-in connectors for Notion, Confluence, PDFs, YouTube, arXiv, Playwright sessions, sitemaps. Your agents can recall what a user told them two sessions ago and what your product documentation says — in the same retrieval call.
RetainDB is a library you add to agents you already have. Letta is a platform you build new agents on. If you have an existing product, the RetainDB path is measured in minutes. The Letta path is measured in sprint cycles.
Yes. Drop-in adapters for Vercel AI SDK, LangChain, LangGraph — or use the REST API directly. npx retaindb-wizard detects your stack and generates the integration code.
Letta's memory integrates tightly with its execution model, which is an advantage if you're running inside Letta. Outside the platform, RetainDB's hybrid retrieval and 88% LongMemEval preference recall gives it the lead on pure memory quality.
88% preference recall on LongMemEval. Under 40ms retrieval. Most teams are in production in under 30 minutes — no infrastructure to manage.
Pages that keep the comparison moving deeper into the RetainDB memory and context cluster.