CopilotKit vs Letta
CopilotKit and Letta are both agent frameworks. CopilotKit is published by CopilotKit and Letta by Letta. On GitHub, CopilotKit has 38,211 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. CopilotKit describes itself as: 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. 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: CopilotKit MIT, Letta Apache-2.0.
Updated Oct 26, 2026 · Built from catalog data; how we rank and grade
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.
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 CopilotKit if you want MCP support built in.
From listing data only. We don't pick a winner on security beyond the grades; read how grades work.
Side by side
| Fact | CopilotKit | Letta |
|---|---|---|
| Type | Harness | Harness |
| Publisher | CopilotKit | 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 | 38,211 | 25,244 |
| Weekly downloads | 286,211 | 40,711 |
| Last release | Oct 16, 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
CopilotKit
npm install @copilotkit/react-core
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 - 0.787score
trueforge
truefoundry
Open-source agent harness that runs the model loop for you, with MCP tools, skills, sandboxing, approvals and a chat UI.
HarnessAFreshness: A★ 6.4K - 0.756score
ai
TanStack
TypeScript SDK for streaming chat, tool-calling agents and structured output across model providers and UI frameworks.
HarnessAFreshness: A★ 3.2K
Questions
- Is CopilotKit or Letta more popular?
- CopilotKit has more GitHub stars (38,211 against 25,244). Stars measure attention, not quality, so check freshness and docs too.
- Are CopilotKit and Letta open source?
- Yes: CopilotKit is MIT and Letta is Apache-2.0.
Related
Cite this page
CopilotKit vs Letta. Agent Mart. https://agentmart.dev/compare/copilotkit-vs-letta (last updated 2026-10-26)