Letta vs Mastra
Letta and Mastra are both agent frameworks for TypeScript. Letta is published by Letta and Mastra by Mastra. On GitHub, Mastra has 29,050 stars and Letta has 25,244. Both were last active in Oct 2026. The table lines up where they differ (publisher, weekly downloads and category) and has the install commands for both. Everything here comes from the listings' public sources and is refreshed daily. Letta describes itself as: Open-source agent harness for stateful agents whose memory persists and improves with use, with a terminal UI, app server and TypeScript SDK. Mastra: TypeScript framework for AI agents and apps with graph-based workflows, memory, suspend-and-resume approvals, MCP servers and model routing. Licenses: Letta Apache-2.0, Mastra unknown.
Updated Oct 26, 2026 · Built from catalog data; how we rank and grade
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.
Mastra
Mastra
TypeScript framework for AI agents and apps with graph-based workflows, memory, suspend-and-resume approvals, MCP servers and model routing.
Who should pick which
- Pick Mastra if you want MCP support built in.
- Pick Mastra 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 | Letta | Mastra |
|---|---|---|
| Type | Harness | Harness |
| Publisher | Letta | Mastra |
| License | Apache-2.0 | License unknown |
| 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 | 25,244 | 29,050 |
| Weekly downloads | 40,711 | 1,442,185 |
| Last release | May 14, 2026 | Oct 21, 2026 |
| Last activity | Oct 18, 2026 | Oct 24, 2026 |
Facts from each listing's public sources, checked daily. Tool lists arrive with tool scans.
Install
Letta
pip install letta
Mastra
npm install @mastra/core
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 - 0.831score
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 - 0.740score
Deep Agents
LangChain
Opinionated agent harness on LangGraph with sub-agents, filesystem access, context management, persistent memory and approval of tool calls.
HarnessAFreshness: A★ 30.6K↓ 1.9M/wk
Questions
- Is Letta or Mastra more popular?
- Mastra has more GitHub stars (29,050 against 25,244). Stars measure attention, not quality, so check freshness and docs too.
- Are Letta and Mastra open source?
- Letta is open source (Apache-2.0); the other is unknown.
Related
Cite this page
Letta vs Mastra. Agent Mart. https://agentmart.dev/compare/letta-vs-mastra (last updated 2026-10-26)