Google Agent Development Kit (ADK) vs Letta
A side-by-side comparison of capabilities, autonomy, integrations, and pricing to help you choose.
Short answer: choose Google Agent Development Kit (ADK) if you want open-source framework for building and orchestrating multi-agent systems (Supervised agent, free); choose Letta if you want open-source framework for stateful ai agents with long-term memory (Supervised agent, freemium).
| Google Agent Development Kit (ADK) | Letta | |
|---|---|---|
| What it is | Open-source framework for building and orchestrating multi-agent systems | Open-source framework for stateful AI agents with long-term memory |
| Type | framework | framework |
| Autonomy | Supervised agent | Supervised agent |
| Pricing | free · Free (open source; pay model + cloud usage) | freemium · Free (open source); Cloud Pro $20/mo + usage |
| Best for | developers, enterprise | developers |
| Deployment | self-hosted, api | self-hosted, saas, api |
| Modalities | text, code, api | text, code, api |
| Models | gemini, model-agnostic | model-agnostic, gpt, claude, open-source |
| Protocols | a2a, mcp, function-calling, rest-api | mcp, rest-api |
| Integrations | Vertex AI, Cloud Run, Gemini, LiteLLM, MCP servers | MCP servers, OpenAI, Anthropic, Ollama, custom tools |
| Capabilities | 3 documented | 4 documented |
Google Agent Development Kit (ADK)
- +Backed by Google with first-class deployment to Vertex AI and Cloud Run
- +Built around the open A2A protocol for cross-framework agent interoperability
- +Model-agnostic via LiteLLM despite Gemini-first defaults
- -A framework, not a product: you build, host, and secure agents yourself
- -Strongest when paired with Google Cloud, which can imply lock-in
Letta
- +Genuinely differentiated memory architecture (self-editing memory blocks from MemGPT research, not a RAG wrapper)
- +Open source under Apache-2.0, self-hostable, and model-agnostic, which avoids lock-in
- +Strong developer ergonomics: REST API, Python and TypeScript SDKs, and the ADE GUI with deep state visibility
- -Positioning has become muddy across research lab, stateful-agents platform, and a Letta Code coding agent
- -Real usage costs climb well beyond the $20 Pro tier once LLM token pass-through is counted
Which should you choose?
Google Agent Development Kit (ADK) is open-source framework for building and orchestrating multi-agent systems, best for developers, enterprise. Letta is open-source framework for stateful ai agents with long-term memory, best for developers. The right choice depends on the autonomy level you want, your existing integrations, and your budget, all compared above.
This comparison is generated from the sourced Google Agent Development Kit (ADK) and Letta profiles. Open either profile to review its evidence and last-reviewed date.