Deep Agents vs Letta
Deep Agents and Letta are both agent frameworks. Deep Agents is published by LangChain and Letta by Letta. On GitHub, Deep Agents has 30,550 stars and Letta has 25,244. Both were last active in Oct 2026. The table lines up where they differ (publisher, license, weekly downloads and category) and has the install commands for both. Everything here comes from the listings' public sources and is refreshed daily. Deep Agents describes itself as: Opinionated agent harness on LangGraph with sub-agents, filesystem access, context management, persistent memory and approval of tool calls. Letta: Open-source agent harness for stateful agents whose memory persists and improves with use, with a terminal UI, app server and TypeScript SDK. Licenses: Deep Agents MIT, Letta Apache-2.0.
Updated Oct 26, 2026 · Built from catalog data; how we rank and grade
Deep Agents
LangChain
Opinionated agent harness on LangGraph with sub-agents, filesystem access, context management, persistent memory and approval of tool calls.
Letta
Letta
Open-source agent harness for stateful agents whose memory persists and improves with use, with a terminal UI, app server and TypeScript SDK.
Who should pick which
- Pick Deep Agents if you work in Python.
- Pick Deep Agents if you want MCP support built in.
- Pick Deep Agents if you need several agents working together.
- Pick Deep Agents if you want a stable release (Letta is marked beta).
From listing data only. We don't pick a winner on security beyond the grades; read how grades work.
Side by side
| Fact | Deep Agents | Letta |
|---|---|---|
| Type | Harness | Harness |
| Publisher | LangChain | Letta |
| License | MIT | Apache-2.0 |
| Pricing | Not stated | Not stated |
| Runs | Not stated | Not stated |
| Auth | Not stated | Not stated |
| Hosts supported | Not stated | Not stated |
| Tools | Not listed yet | Not listed yet |
| Security grade | –Security: not graded yet | –Security: not graded yet |
| Freshness grade | AFreshness: A | AFreshness: A |
| GitHub stars | 30,550 | 25,244 |
| Weekly downloads | 1,930,228 | 40,711 |
| Last release | Oct 23, 2026 | May 14, 2026 |
| Last activity | Oct 24, 2026 | Oct 18, 2026 |
Facts from each listing's public sources, checked daily. Tool lists arrive with tool scans.
Install
Deep Agents
pip install deepagents
Letta
pip install letta
Also consider
- 0.867score
Pi Agent Core
Earendil
Minimal TypeScript agent harness with an agent runtime, multi-provider LLM API, terminal UI and coding agent CLI that users extend themselves.
HarnessAFreshness: A★ 117.6K↓ 5.1M/wk - 0.853score
LlamaIndex
LlamaIndex
Open-source Python toolkit for RAG and agents over your own data, with event-driven workflows and 300+ integration packages.
HarnessAFreshness: A★ 52.6K↓ 1.4M/wk - 0.831score
CopilotKit
CopilotKit
Open-source SDK that connects AI agents to app front ends with chat UI, generative UI, shared state and human approvals; creator of the AG-UI protocol.
HarnessAFreshness: A★ 38.2K↓ 286.2K/wk
Questions
- Is Deep Agents or Letta more popular?
- Deep Agents has more GitHub stars (30,550 against 25,244). Stars measure attention, not quality, so check freshness and docs too.
- Are Deep Agents and Letta open source?
- Yes: Deep Agents is MIT and Letta is Apache-2.0.
Related
Cite this page
Deep Agents vs Letta. Agent Mart. https://agentmart.dev/compare/deep-agents-vs-letta (last updated 2026-10-26)