LLM Agents

developer platform

Build and deploy stateful AI agents

Use the Letta API to build agents that can actually remember and learn about your users over time. Our agents deploy and scale effortlessly, run forever, and learn like humans.

Open source, production ready, and fully model-agnostic.

Start building Read documentation

Introducing the Agent Developer Environment (ADE)

Visualize your agent's memory, reasoning steps, and tool calls in a fully transparent no-code UI.

agent development environment (ADE)

Agent API and SDKs

Connect your agents to your application using your favorite language or framework.

View developer quickstart

from letta_client import Letta
import os

client = Letta(api_key=os.getenv("LETTA_API_KEY"))

agent_state = client.agents.create(
    model="openai/gpt-4.1",
    embedding="openai/text-embedding-3-small",
    memory_blocks=[
        {
          "label": "human",
          "value": "Name: Timber. Status: dog. Occupation: building Letta, infrastructure to democratize self-improving superintelligence"
        },
        {
          "label": "persona",
          "value": "I am a self-improving superintelligence. Timber is my best friend and collaborator."
        }
    ],
    tools=["web_search", "run_code"]
)

print(f"Agent created with ID: {agent_state.id}")

import Letta from "@letta-ai/letta-client";

const client = new Letta({ apiKey: process.env.LETTA_API_KEY });

const agentState = await client.agents.create({
  model: "openai/gpt-4.1",
  embedding: "openai/text-embedding-3-small",
  memory_blocks: [
    {
      label: "human",
      value:
        "Name: Timber. Status: dog. Occupation: building Letta, infrastructure to democratize self-improving superintelligence",
    },
    {
      label: "persona",
      value:
        "I am a self-improving superintelligence. Timber is my best friend and collaborator.",
    },
  ],
  tools: ["web_search", "run_code"],
});

console.log("Agent created with ID:", agentState.id);

import { lettaCloud } from '@letta-ai/vercel-ai-sdk-provider';
import { generateText } from 'ai';

const result = await generateText({
  model: lettaCloud(),
  providerOptions: {
    letta: {
      agent: { id: 'your-agent-id' },
    },
  },
  prompt: 'Write a vegetarian lasagna recipe for 4 people.',
});

console.log(result.text);

Customer stories

Customer Case study

What Letta allowed us to do is rapidly iterate on this system. I could just prototype much faster. I was able to see the product working right away.

Vansh Khanna

Member of Technical Staff, Kognitos

Letta makes it easy to deploy and manage a huge fleet of agents with a single API endpoint, which is critical for our application where we are creating personalized agents for every user.

James Kirk

VP of AI at Hunt Club

What Letta allowed us to do is rapidly iterate on this system. We changed our design multiple times throughout the process without having to throw everything away with each new iteration.