- Developers building personalized stateful agents
- Teams that need memory APIs and SDKs instead of ad hoc context prompts
- Researchers exploring learning and self-improving agents
Memory Systems
Letta
Platform for stateful agents with advanced memory, personalization, and learning over time.
Apache-2.0 License
Open sourceSelf-hostedAPI
About
Letta overview
Letta is an open-source platform for building stateful agents that remember users, maintain memory blocks, and interact through APIs and SDKs.
Stateful agent model
Letta treats memory as part of the agent state rather than a loose prompt append.
That makes it easier to build agents that remain coherent across sessions.API and SDK surface
Letta provides APIs and client SDKs for integrating stateful agents into applications.
Product teams need stable interfaces, not just demos.Active open-source platform
The project has frequent releases and documentation around agents and memory.
Active maintenance matters for infrastructure that sits inside an application. Use cases
When to use Letta
Personalized AI agents
Build assistants that retain a persona and user-specific memory blocks.
Stateful agent APIs
Expose memory-backed agents inside applications through a service interface.
Learning workflows
Experiment with agents that improve from ongoing interactions.
Compare
How it compares
Choose Letta for stateful agent architecture vs standalone memory APIs
Letta is broader than memory storage; it is closer to a platform for agents whose behavior depends on state.
FAQ
Questions
What should I check before using Letta?
Test Letta with repeated sessions. Add facts, update them, ask for recall, inspect retrieval behavior, and verify deletion or scoping controls before storing sensitive user or project memory.
Is Letta open source?
Letta is listed with Apache-2.0 based on the official source links in this profile. Re-check the repository, model card, or docs before production use.
Who should evaluate Letta?
Letta is most worth evaluating for developers building personalized stateful agents.
Tags
Capabilities
Decision brief
JSON
Should you use Letta?
- Users who want a fully managed consumer product with no setup work
- Teams that cannot review the linked source, license, and operational requirements before adoption
- Verified 2026-04-19
- License: Apache-2.0
- Repo: letta-ai/letta
- Open-source signal
Deployment
self hosted, cloud
Permission surface
memory, external services
Decision signals
Self-hostable, API
Agent packet
Structured decision data for Letta
This packet is the compact machine-readable view agents should use before following source links or taking action.
Capabilities
memory, state management, workflow orchestration
Constraints
open source, self hosted
Deployment
self hosted, cloud
Permission surface
memory, external services
Recommended workflows
Connector or protocol layer, Memory or RAG workflow, Reusable skill workflow
Overview
What Letta does
What it is
Letta is an open memory-system resource to evaluate by what it stores, how recall works, how memory is scoped, and whether users or teams can inspect, correct, export, or delete durable context.
Why it matters
Letta matters because memory is not just a database problem; it changes how an agent behaves over time. Letta gives builders a more structured model for stateful agents and persistent memory.
How to evaluate it
Test Letta with repeated sessions. Add facts, update them, ask for recall, inspect retrieval behavior, and verify deletion or scoping controls before storing sensitive user or project memory.
Facts
Known metadata and operating surface
These fields are separated from editorial interpretation so agents can reason over facts and missing checks.
Resource type memory system
Category Memory Systems
Maturity active
Difficulty Unknown
License Apache-2.0
Pricing open source
Verified 2026-04-19
Source confidence high
Risk level moderate
Fit matrix
Where Letta fits in an agent stack
strong
Connector or protocol layer
Letta has multiple signals for connector or protocol layer, including matching tags, capabilities, category, or positioning.
- Connect one low-risk service, then inspect schemas, auth scope, errors, and logs.
- Confirm official docs, current maintenance, license, and runtime constraints before production use.
strong
Memory or RAG workflow
Letta has multiple signals for memory or rag workflow, including matching tags, capabilities, category, or positioning.
- Create, update, retrieve, correct, and delete memory or retrieval objects with real data.
- Confirm official docs, current maintenance, license, and runtime constraints before production use.
strong
Reusable skill workflow
Letta has multiple signals for reusable skill workflow, including matching tags, capabilities, category, or positioning.
- Run one skill end to end and check whether it produces evidence or structured output.
- Confirm official docs, current maintenance, license, and runtime constraints before production use.
partial
Browser automation
Letta has at least one signal for browser automation, but should be checked against a real task before adoption.
- Run one non-sensitive website task and inspect clicks, waits, retries, and changed URLs.
- Confirm official docs, current maintenance, license, and runtime constraints before production use.
partial
Coding agent workflow
Letta has at least one signal for coding agent workflow, but should be checked against a real task before adoption.
- Run a small repository change and inspect the diff, tests, and rollback path.
- Confirm official docs, current maintenance, license, and runtime constraints before production use.
partial
Evaluation and observability
Letta has at least one signal for evaluation and observability, but should be checked against a real task before adoption.
- Add one repeatable test case and confirm results can run again in review or CI.
- Confirm official docs, current maintenance, license, and runtime constraints before production use.
Inputs and outputs
What an agent should inspect
Likely inputs
- Repositories, files, issues, terminal output, and test results
- Documents, user facts, entities, context, or retrieval queries
- Tool schemas, API requests, service resources, and auth scopes
- Official setup instructions and a small real workflow
Likely outputs
- Diffs, commits, explanations, test results, or review notes
- Retrieved context, memory updates, graph relations, or citations
- A decision on whether this resource fits the target workflow
Evidence
Sources, claims, and missing checks
Claims are marked separately from source links so future crawlers and reviewers can update them without rewriting the page.
GitHub github
Repository source for code, license, issues, releases, and implementation details.
Homepage homepageOfficial or project-controlled source for this resource profile.
Docs docsDocumentation source for setup, API shape, and operational behavior.
Letta is listed as open source.
License metadata: Apache-2.0Letta has a recorded GitHub repository: letta-ai/letta.
Resource facts and GitHub source link.Letta supports these recorded deployment modes: self hosted, cloud.
OpenAgent decision signal metadata.Letta is tagged with memory, state management, workflow orchestration capabilities.
OpenAgent capability taxonomy.- Repository freshness has not been recorded.
Next action
How to start evaluating Letta
Inspect repository
Check license, recent activity, issues, examples, and security-sensitive code paths.
Open sourceOpen Homepage
Start from the official source before adopting third-party instructions.
Open sourceRead setup docs
Use docs as the source of truth for installation and supported interfaces.
Open sourceClone Letta
Use the official documentation for the current server, API, and SDK setup path.
git clone https://github.com/letta-ai/letta.git Compare
Alternatives and nearby resources
Use related resources to compare category fit, license, deployment model, and first-workflow behavior.
FAQ
Common questions about Letta
What should I check before using Letta?
Test Letta with repeated sessions. Add facts, update them, ask for recall, inspect retrieval behavior, and verify deletion or scoping controls before storing sensitive user or project memory.
Is Letta open source?
Letta is listed with Apache-2.0 based on the official source links in this profile. Re-check the repository, model card, or docs before production use.
Who should evaluate Letta?
Letta is most worth evaluating for developers building personalized stateful agents.