Both sit in the framework layer with similar commercial terms, so the practical split is language: Pydantic AI targets Python and LlamaIndex targets Python.
Type-safe Python agents with structured output that actually validates.
Data-first framework — ingestion, indexing and RAG-heavy agents.
| Pydantic AI | LlamaIndex | |
|---|---|---|
| Licence | Open source | Open source |
| Pricing | open source | freemium |
| Self-hostable | Yes | Yes |
| Languages | Python | Python, TypeScript |
| Install | pip install pydantic-ai | pip install llama-index |
| Keys required | None | None |
Both sit in the framework layer with similar commercial terms, so the practical split is language: Pydantic AI targets Python and LlamaIndex targets Python. Pydantic AI: Type-safe Python agents with structured output that actually validates. LlamaIndex: Data-first framework — ingestion, indexing and RAG-heavy agents.
Pydantic AI can run on your own infrastructure. LlamaIndex can run on your own infrastructure.
Pydantic AI is open source (open source). LlamaIndex is open source (freemium).
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/compare/pydantic-ai-vs-llamaindex