LlamaIndex vs Letta (formerly MemGPT)
Detailed side-by-side comparison to help you choose the right tool
LlamaIndex
🔴DeveloperAI agent framework
LlamaIndex is an open-source Python and TypeScript framework for building RAG, document workflows, and AI agents — with LlamaCloud for managed parsing, extraction, and indexing.
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FreeLetta (formerly MemGPT)
🔴DeveloperAI Knowledge Tools
AI memory platform for building stateful agents that can preserve selected context across sessions, manage long conversations, and support applications that need durable agent memory.
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Free ($0/month)Feature Comparison
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💡 Our Take
Choose Letta if the product needs stateful agent memory that changes across sessions. Choose LlamaIndex if your main requirement is building retrieval-augmented generation over documents, databases, or knowledge stores.
LlamaIndex - Pros & Cons
Pros
- ✓Best-in-class retrieval strategies: hybrid, parent-child, summary indexes, knowledge graphs
- ✓LlamaParse is the strongest PDF/document parser for enterprise RAG today
- ✓Open-source library is MIT-licensed and runs anywhere
- ✓Workflows agent layer is a clean alternative to LangGraph for stateful task graphs
- ✓10,000 free LlamaCloud credits make evaluation painless
Cons
- ✗LlamaCloud paid pricing is credit-based and harder to model than seat pricing
- ✗Workflows ecosystem is younger than LangGraph's; fewer multi-agent examples in the wild
- ✗Library API has churned over major releases — older tutorials are often out of date
- ✗Visual builder UX is not part of the product; teams that want no-code go elsewhere
- ✗Pure agent orchestration with complex branching is still cleaner in LangGraph
Letta (formerly MemGPT) - Pros & Cons
Pros
- ✓Purpose-built for persistent agent memory, making it a stronger fit than stateless chat tools for assistants that need to remember users, preferences, and prior work across sessions.
- ✓Supports both cloud-hosted and self-hosted deployment according to the existing directory record, giving technical teams a path for managed usage or more direct infrastructure control.
- ✓Model-agnostic positioning allows teams to design around an agent memory layer instead of tying all context and behavior to a single LLM provider.
- ✓Its virtual context approach addresses a concrete limitation of LLM applications: important information can outlive the immediate context window instead of being lost between sessions.
- ✓The existing listing identifies 5 core feature areas, including persistent memory, virtual context, self-editing agents, document analysis beyond context limits, and multi-session conversation tracking.
- ✓Compared to broader agent frameworks in our directory, Letta has a clearer focus on long-running, stateful agents rather than general workflow orchestration.
Cons
- ✗The provided scraped website content did not expose complete current customer counts, founding year, or integration counts, so buyers should verify commercial details before procurement.
- ✗Persistent memory adds design and governance complexity because teams must decide what agents should store, retrieve, update, or forget over time.
- ✗Usage-based charges on the API Plan, including $0.10 per active agent per month and $0.00015 per second for server-side tool execution, can make costs harder to forecast for high-volume applications.
- ✗Self-hosted deployment can require engineering resources for installation, model provider configuration, monitoring, upgrades, and data management.
- ✗Letta is more specialized than broad frameworks like LangChain or Semantic Kernel, so teams that mainly need general tool orchestration may find its memory-first focus narrower.
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