# Letta — Stateful agent harness, cloud and SDK for agents with persistent, git-versioned memory. > Source: The Agents Index — https://theagentsindex.com/letta (structured, researched, re-verified) > Facts last verified: 2026-09-02 Letta is a platform for stateful agents whose identity and git-versioned memory persist across models, machines and conversations. It ships as an open-source harness with CLI, desktop and web apps, a TypeScript Agent SDK, and a hosted cloud. | Fact | Value | | --- | --- | | Website | https://www.letta.com | | Price | from $20/month | | Free tier | Yes | Free plan is $0/month with limited agents (3 stateful agents), limited Letta Auto usage and rotating free models; BYOK and external coding plans are supported. The local backend runs with no Letta account at all. ## What it does **Writes code** · Yes — Agents edit and create files in your repository, including from GitHub issues and PRs. > Read and search files in your repository Make edits and create new files Run shell commands (git, npm, etc.) > — https://docs.letta.com/platform/github-action/index.md · Capabilities section, "What it can do" list **Debugs and fixes** · Yes — Vendor states coding agents debug failures and run test suites. > They can review pull requests, run test suites, debug failures, and maintain documentation. > — https://docs.letta.com/handbook/index.md · "What people build" section, Coding partners paragraph **Writes tests** · Partly — Vendor claims agents run test suites; it never claims they author tests. > They can review pull requests, run test suites, debug failures, and maintain documentation. > — https://docs.letta.com/handbook/index.md · What people build section, Coding partners paragraph **Reviews code** · Yes — Reviews diffs on demand or on every PR via the GitHub action's prompt input. > prompt: "Review this PR for bugs and security issues" > — https://docs.letta.com/platform/github-action/index.md · Automated workflows section, auto-review workflow YAML **Whole-codebase work** · Partly — Subagents read across large repositories and memory persists project knowledge, but no repo-wide migration claim. > That subagent may use hundreds of thousands of tokens to read hundreds of files, but the main agent will only see the final answer > — https://docs.letta.com/configuration/subagents/index.md · How it works section, codebase-search example **Ships it** · Partly — Commits, pushes and opens pull requests; it cannot approve PRs and no deployment step is claimed. > Commit and push changes Create pull requests > — https://docs.letta.com/platform/github-action/index.md · Capabilities section, "What it can do" list ## How much it does unattended **Runs autonomously** · Yes — Headless CLI runs, scheduled prompts and subagents execute without a human turn; unrestricted mode auto-allows tools. > The subagent runs autonomously with its own system prompt, tools, and model. > — https://docs.letta.com/configuration/subagents/index.md · How it works section, second paragraph **Multi-agent** · Yes — Seven built-in subagent types plus deploying any existing stateful agent as a subagent, in parallel or background. > It is also possible to deploy an arbitrary Letta agent as a subagent by specifying its agent_id. > — https://docs.letta.com/configuration/subagents/index.md · Launching stateful agents as subagents section **Agent permissions** · Yes — Four modes from strict to unrestricted, plus allow/deny tool patterns and a cross-agent memory guard. > standard | Ask before running tools that require approval, such as shell commands, edits, and subagents > — https://docs.letta.com/configuration/permissions/index.md · Permission modes table, standard row ## Which models it runs on **Claude** · Yes — Anthropic API, Amazon Bedrock and GitHub Copilot connections; supported both locally and signed in with Letta. > Letta agents are model-agnostic. Agents can use Claude, GPT, Gemini, or other supported models. > — https://docs.letta.com/configuration/models/index.md · Opening paragraph **GPT** · Yes — OpenAI API keys and ChatGPT Plus/Pro Codex subscriptions both connect; toolsets switch per model family. > ChatGPT Plus/Pro Codex | Subscription | Subscription > — https://docs.letta.com/configuration/models/index.md · Supported providers table, ChatGPT Plus/Pro Codex row **Open models** · Yes — Ollama, LM Studio and llama.cpp endpoints are local-only integrations; DeepSeek, Mistral and Together are also listed. > direct integrations with local inference providers such as LM Studio, Ollama, and llama.cpp are available only for local agents > — https://docs.letta.com/configuration/models/index.md · Connecting model providers section, gateway paragraph **Model choice** · Yes — You pick the model and can switch mid-conversation; memory travels with the agent across providers. > Users can change an agent's underlying model at any time, even mid-conversation. > — https://docs.letta.com/configuration/models/index.md · Opening paragraph ## Where you use it **In your editor** · Yes — The letta-acp adapter runs Letta as a custom agent in Zed, JetBrains IDEs and Obsidian. > Editors with ACP support can launch letta-acp as a custom agent. The following examples cover Zed, JetBrains IDEs, and Obsidian > — https://docs.letta.com/platform/acp/index.md · Use ACP in an editor section **On the command line** · Yes — The primary surface is a terminal harness installed from npm, with headless mode for automation. > Run the following command to install the Letta CLI via your terminal (requires Node.js version 22.19+) > — https://docs.letta.com/platform/cli/index.md · Getting started, step 1 **In your pipeline** · Yes — A GitHub Action triggers agents from issues and PR comments, or automatically on pull_request events. > The Letta Code GitHub action lets you trigger Letta agents directly from GitHub issues and pull requests. > — https://docs.letta.com/platform/github-action/index.md · Introduction paragraph **In a browser** · Yes — chat.letta.com serves cloud-hosted agents only; self-hosted agents are not reachable there. > The web app works only with agents hosted in Letta Cloud. > — https://docs.letta.com/reference/faq/index.md · Web app (chat.letta.com) section ## Whose machine it runs on **Self-hosted** · Yes — Local runtime keeps all state on-device with no account, or run the App Server via Docker, Railway or Fly.io. > all agent state, including messages, memory, and provider connections, stays on-device, and no Letta account is required. > — https://docs.letta.com/self-hosting/index.md · Local runtime bullet, opening section **Open source** · Yes — The harness and Agent SDK are Apache-2.0 on GitHub; Letta Cloud itself is a hosted proprietary service. > The Letta agent harness is fully open source and builds on our lab's latest research in AI memory and continual learning. > — https://docs.letta.com/llms.txt · Opening blockquote ## What it costs to run **How it meters** · Yes — Per seat on personal and Teams plans; the API plan meters per active agent, per second of tool execution and per token. > $0.10 / active agent / mo $0.00015 / sec tool execution > — https://docs.letta.com/pricing/index.md · Plans, Developer Plans tab, API Plan card **Free tier** · Yes — Free $0 plan with limited agents and Letta Auto usage; the local backend needs no account at all. > Free plans are limited to 3 stateful agents. > — https://docs.letta.com/pricing/index.md · For Individuals section **API access** · Yes — Cloud agents are drivable via the Letta REST API with an API key; the recommended path is the TypeScript Agent SDK. > Agents hosted in Letta Cloud are also accessible through the Letta REST API using a LETTA_API_KEY. > — https://docs.letta.com/reference/faq/index.md · App Server section, "Is there a REST API?" **MCP server** · No — MCP runs inbound only: Letta sessions consume stdio, HTTP and SSE MCP servers; no Letta MCP server is published. > MCP tools are discovered from servers supplied through mcpServers and proxied by the SDK host to the MCP server. > — https://docs.letta.com/agent-sdk/mcp/index.md · Opening list, MCP tools bullet **Bring your own key** · Yes — Every plan supports your own provider keys or coding subscriptions, and usage then bypasses Letta credits. > Yes. All plans support bringing your own API keys (BYOK). When you connect your own keys (via /connect in the Letta CLI), usage goes directly through your provider account > — https://docs.letta.com/pricing/index.md · Frequently asked questions, "Can I use my own API keys?" ## Buying it for a team **A company can buy it** · Yes — Teams Pro is sold per seat at $20/seat/month; Enterprise is a custom volume quote. > Teams Pro For teams $20 /seat/month > — https://docs.letta.com/pricing/index.md · Plans, Teams / Enterprise tab, Teams Pro card **Seat model** · Partly — Priced per seat on Teams Pro; no seat minimum or maximum is published, and Enterprise seat pricing is by contact. > If you would like to configure managed per-seat pricing for your business, please contact us > — https://docs.letta.com/pricing/index.md · Teams / Enterprise tab, line below the Enterprise card **Pooled budget** · No — Quota attaches to each purchased Pro seat; unpaid seats get no Letta-hosted inference at all. > By default, users you add will be on Free seats, which means they will be unable to use Letta-hosted models for inference. > — https://docs.letta.com/teams/quickstart/index.md · Creating a team, step 3 'Add seats' **Admin controls** · Partly — Org roles gate who reaches an agent; what the agent may run is set per machine or project, not centrally by an admin. > Agent access and tool permissions are separate. Sharing an agent does not automatically allow every tool call on every connected computer. Each computer still applies its own approval rules > — https://docs.letta.com/teams/permissions/index.md · Tool permissions section **Audit log** · No — No administrative audit log is published; the Enterprise list stops at RBAC, SSO, quotas and dedicated support. > Volume-based pricing Increased quotas Role-based access control SAML/OIDC SSO Dedicated support > — https://docs.letta.com/pricing/index.md · Teams / Enterprise tab, Enterprise card feature list **Single sign-on** · Partly — SAML/OIDC SSO is an Enterprise-only line item; Pro and Teams Pro cards do not list it. > SAML/OIDC SSO > — https://docs.letta.com/pricing/index.md · Teams / Enterprise tab, Enterprise card feature list ## What happens to your code **Opt out of training** · Partly — Hosted messages may train future models; running your own model backend or local state means nothing is collected. > We do NOT collect data on any of your messages or prompts unless you are using our hosted services (for example, if you are running your own model backends, this data will never be collected). > — https://www.letta.com/privacy-policy/ · Overview bullets at top of policy **Data residency** · Partly — You choose the machine, local or your own App Server host, but no Letta Cloud region or jurisdiction is published. > Agent state and the execution environment live on the App Server machine, so multiple clients can share the same agents and the server can run on different infrastructure than your application. > — https://docs.letta.com/self-hosting/index.md · Agent SDK section, Remote backend bullet **Getting out** · Partly — Memory is git-backed files you can inspect and sync to your own GitHub repo; credit expiry is never stated. > Agent memory is represented as git-backed files that you can inspect, edit, and version. > — https://docs.letta.com/handbook/index.md · Why Letta? section, Living memory bullet **Certifications** · Partly — GDPR and US state privacy rights are documented; no SOC 2 or ISO 27001 attestation appears anywhere on the site. > If you are located in a country that falls under the scope of the GDPR, data protection laws give you certain rights with respect to your personal data > — https://www.letta.com/privacy-policy/ · Your Rights section, GDPR subsection ## Platform record (as of 2026-08-30) Reported by the code-hosting platform, not by the vendor. | Fact | Value | | --- | --- | | Licence | Apache-2.0 | | Stars | 3155 | | Forks | 381 | | Last push | 2026-08-30 | ## Provenance 1 of 19 sources behind the facts above are independent of the vendor. ## Coverage elsewhere Pages about this product that the vendor does not control. The label states how independent each one is. | Source | Kind | Read | | --- | --- | --- | | crunchbase.com | Platform record | 2026-08-23 | ## What changed - 2026-09-02 — Capabilities · Commercial terms · Free tier - 2026-08-31 — Capabilities · Commercial terms · Free tier · Price - 2026-08-23 — Alternatives · Crunchbase link · LinkedIn link · One-liner · Repository · Summary - 2026-08-19 — One-liner · Summary ## Correcting this record Anything marked "Not established" is a question we have not answered — it is not a No. If you represent Letta, or anything here is wrong or out of date, you can supply it with a source: the operations this site accepts from an agent are listed at https://theagentsindex.com/.well-known/agents.json — that catalogue needs no key to read, and each entry states its own auth. Supplying evidence is free. Nothing that can be bought here changes what a field says, whether a gap is closed, or how this record is scored.