Build agents that learn
Letta is the platform for building stateful agents: AI that can continually learn from experience and evolve over time.
Letta developer platform
Agents API
Build model-agnostic agents with advanced memory that can continually learn and self-improve from experience and data.
ADE
Use the Agent Development Environment (ADE) to visualize your agent's memory, reasoning, and tool calls in real-time.
BACKED BY RESEARCH, Trusted by developers
Today's AI agents struggle to remember previous mistakes, and are unable to learn from new experiences. The Letta Developer Platform lets you build long-running, stateful agents that self-improve and get better with use.
Agents as APIs
Letta agents are exposed as a REST API endpoints, ready to be integrated into your applications - auth and identities included.
Stateful Agents
Letta persists all state automatically in a model-agnostic representation. Move agents between LLM providers without losing their memories.
Backed by Research
Letta manages context and memory with techniques designed by AI PhDs from UC Berkeley, including the creators of MemGPT.
Framework agnostic
Program your agents and connect them to your applications through Letta’s Agents API, SDKs, and framework integrations.
from letta_client import Letta
client = Letta(token="LETTA_API_KEY")
agent_state = client.agents.create(
model="openai/gpt-4.1",
embedding="openai/text-embedding-3-small",
memory_blocks=[
{
"label": "human",
"value": "The human's name is Chad. They like vibe coding."
},
{
"label": "persona",
"value": "My name is Sam, the all-knowing sentient AI."
}
]
)import { LettaClient } from '@letta-ai/letta-client'
const client = new LettaClient({ token: "LETTA_API_KEY" });
const agentState = await client.agents.create({
model: "openai/gpt-4.1",
embedding: "openai/text-embedding-3-small",
memoryBlocks: [
{
label: "human",
value: "The human's name is Chad. They like vibe coding."
},
{
label: "persona",
value: "My name is Sam, the all-knowing sentient AI."
}
]
});import { lettaCloud } from '@letta-ai/vercel-ai-sdk-provider';
import { generateText } from 'ai';
const { text } = await generateText({
model: lettaCloud('your-agent-id'),
prompt: 'Write a vegetarian lasagna recipe for 4 people.',
});import { LettaClient } from '@letta-ai/letta-client'
const client = new LettaClient({ token: "LETTA_API_KEY" });
const agentState = await client.agents.create({
model: "openai/gpt-4.1",
embedding: "openai/text-embedding-3-small",
memoryBlocks: [
{
label: "human",
value: "The human's name is Chad. They like vibe coding."
},
{
label: "persona",
value: "My name is Sam, the all-knowing sentient AI."
}
]
});import { LettaClient } from '@letta-ai/letta-client'
const client = new LettaClient({ token: "LETTA_API_KEY" });
const agentState = await client.agents.create({
model: "openai/gpt-4.1",
embedding: "openai/text-embedding-3-small",
memoryBlocks: [
{
label: "human",
value: "The human's name is Chad. They like vibe coding."
},
{
label: "persona",
value: "My name is Sam, the all-knowing sentient AI."
}
]
});Production-ready, proven at scale
Scale from prototypes to millions of agents, all on the same stack. Ensure that your data, state, and agent memories are safe from vendor lock-in.
Get started today
GitHub
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Stay up to date with Letta
Oct 30, 2025
Context-Bench: Benchmarking LLMs on Agentic Context Engineering
We are open-sourcing Context-Bench, which evaluates how well language models can chain file operations, trace entity relationships, and manage multi-step information retrieval in long-horizon tasks.
