Letta

Letta is a memory-first AI agent framework that enables persistent, stateful, and self-improving agents across different LLM providers. It solves the stateless problem of standard LLMs by providing a tiered memory architecture that allows agents to evolve and retain context over time. It is the bridge between simple chatbot interfaces and production-grade, stateful AI systems.

The platform provides both a visual Agent Development Environment for Vibe Builders and a REST API with SDKs for Developers. Letta supports local models alongside frontier providers like OpenAI and Anthropic. The platform includes a CLI for local development and supports self-hosting for teams requiring full infrastructure control.

The API is available for production-grade integration, and the system is open-source for those who need to deploy and maintain their own infrastructure. What Letta does:

• •Persistent long-term memory Letta agents retain context across sessions by storing information in a tiered memory architecture that mimics human recall.
• •Visual Agent Development Environment Vibe Builders can debug, version, and manage agent personas through a visual interface rather than relying solely on code.
• •Letta Code runtime This feature provides git-backed context repositories and filesystem-style access for coding agents to manage complex projects.
• •Multi-step task orchestration Agents autonomously manage background memory updates and execute complex workflows without manual intervention.
• •Unified model-agnostic API Connect your agents to OpenAI, Anthropic, or local LLM providers through a single, consistent interface.
• •Sub-agent architectures Build hierarchical agent systems where specialized sub-agents handle specific tasks while maintaining shared memory.

Pricing:

• •Free Up to 3 agents for personal exploration and small-scale testing.
• •Pro $20/mo for up to 20 agents with increased memory capacity.
• •Max Lite $100/mo for up to 50 agents designed for power users.
• •Max $200/mo for high-volume usage with increased quotas and priority support.
• •API Plan $20/mo base fee plus $0.10 per active agent per month and $0.00015 per second of tool execution, requiring users to cover their own LLM provider costs.

Limitations:

• •Steep learning curve for non-technical users Letta requires familiarity with API key management and agent configuration, making it unsuitable for users without a technical background.
• •Infrastructure maintenance for self-hosting While the platform is open-source, self-hosting requires significant engineering effort to manage the underlying stateful infrastructure and database persistence.
• •Cost complexity for high-volume API usage The granular pricing model for tool execution can lead to unpredictable monthly bills if agent activity is not carefully monitored and optimized.