Library / SDK
Guardrails & Structure
BAML
1A 2language 3for 4structured 5LLM 6functions
the six Ws · specification
W1
Who
Maintained by Boundary (BoundaryML).
W2
What
A language for writing reliable structured-output LLM functions.
W3
Where
A DSL compiled into Python, TypeScript, and other clients.
W4
When
When you need typed, schema-checked LLM outputs.
W5
Why
Treats prompts as typed functions with tests and streaming.
W6
With
The BAML toolchain and an LLM provider.
W7
Watch
Company-maintained; open-source (Apache-2.0). Generated clients run in your app and call the LLM provider you configure.