# Letta

> Stateful agents from the MemGPT creators — an Apache-2.0 server with self-editing memory, and Letta Code, the memory-first model-agnostic coding harness.

Letta (formerly MemGPT, Apache-2.0, ~23k stars) builds agents that manage their own memory — self-editing memory blocks, conversation search, persistence beyond any context window — exposed as an agents server/API with Python/TS SDKs and a visual Agent Development Environment. Its March 2026 pivot made Letta Code the flagship: a memory-first, model-agnostic coding harness.

Website: https://www.letta.com

Letta carries the most cited lineage in agent memory: it *is* MemGPT — the Berkeley project that framed an agent's context as an OS problem (paging, self-editing memory, persistence) — grown into a company. In 2026 its center of gravity shifted from platform to **harness**: Letta Code, a coding agent whose differentiator is that it genuinely remembers.

## Highlights

- **Self-editing memory** — agents maintain core memory blocks (persona, user, task state) they rewrite themselves, plus searchable archival history: the MemGPT design, productionized.
- **Stateful by default** — agents persist across sessions and beyond context limits; state lives server-side, not in the transcript.
- **Letta Code** — the memory-first coding harness: `/init` builds codebase memory, `/remember` captures lessons, skills accrue from experience; model-agnostic across Claude/GPT/Gemini and open models, with vendor-cited top OSS-harness results on Terminal-Bench.
- **Agent Development Environment** — a visual builder/debugger where you watch and edit an agent's memory and state directly.
- **Apache-2.0 core** — server and harness open; Python/TypeScript SDKs for embedding stateful agents in your own products.

## In an AI-assisted workflow

```bash
npm install -g @letta-ai/letta-code && letta    # the harness
# or embed: pip install letta-client — stateful agents via the Letta API
```

The distinctive loop: run it on a repo for a week and the agent's memory of *your* codebase — conventions, gotchas, past decisions — compounds, the dimension where [stateless harnesses](/guides/comparisons/claude-code-vs-opencode) start fresh each session.

> [!NOTE]
> The March 2026 pivot retired chunks of the older platform (server-side tools, templates, filesystem abstractions) in favor of the Letta Code direction — pre-2026 tutorials are partially stale, and pricing is now framed around the harness. Heavy daily coding can exceed the Pro quota into pay-as-you-go; BYO keys on the free tier sidesteps metering.

## Good to know

~23k stars on the core (the homepage's old MemGPT counter undersells it), $10M Felicis-led seed at the 2024 rename. Against the memory-layer alternatives — [Mem0](/tools/mem0)'s drop-in API, [Zep](/tools/zep)'s temporal graphs — the trade is adopt-the-runtime versus add-the-layer: [Mem0 vs Zep vs Letta](/guides/comparisons/mem0-vs-zep-vs-letta) draws it out.

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_Source: https://agentscamp.com/tools/letta — Tool on AgentsCamp._