The library you write orchestration in, when an off-the-shelf harness is not enough.
| Option | What it does | Licence | Self-host |
|---|---|---|---|
| LangGraph | Graph-shaped orchestration with checkpointing, interrupts and human-in-the-loop. | Open source | Yes |
| Mastra | TypeScript agent framework with workflows, memory, evals and a local playground. | Open source | Yes |
| Pydantic AI | Type-safe Python agents with structured output that actually validates. | Open source | Yes |
| CrewAI | Role-based crews of agents with delegation between them. | Open source | Yes |
| Agno | Fast, lightweight multi-agent runtime with built-in memory and knowledge. | Open source | Yes |
| LlamaIndex | Data-first framework — ingestion, indexing and RAG-heavy agents. | Open source | Yes |
| DSPy | Programs, not prompts — compile and optimise the prompt against a metric. | Open source | Yes |
| Vercel AI SDK | Streaming-first TypeScript SDK with a unified provider interface and UI hooks. | Open source | Yes |
The library you write orchestration in, when an off-the-shelf harness is not enough. It is optional; plenty of working agents skip it.
This registry tracks 8. 8 are open source and 8 can run on your own infrastructure.
It depends on constraints rather than preference: whether you must self-host, whether the budget allows a hosted service, and which language your team writes. Describe what you are building and the advisor fills this layer along with the other 9.
Every page here answers to Accept: text/markdown and returns the same content at roughly a tenth the tokens. No separate site, no toggle — same URL.
curl -s -H "Accept: text/markdown" https://newagent.build/layers/framework