ax-llm/ax

What is it?

Key features

• 01Typed structured output from string DSL, fluent builder, or Zod/Valibot/ArkType schemas
• 02Unified API across many model providers, switched by a profile name
• 03Agents with sandboxed JS runtime, checkpointed replay, and memory and skill loading
• 04Typed workflow graphs with branches, loops, and parallel execution
• 05Optimizers including GEPA and few-shot bootstrapping
• 06Streaming parsing, tool calling, and MCP client support

Use cases

• Extracting structured data from emails, tickets, or documents into typed objects
• Building TypeScript applications that call LLMs with validated outputs
• Creating multi-step LLM pipelines with branching and retry logic
• Tuning prompts automatically against a labeled evaluation set

Quick start

1. 1

   Install the TypeScript package from npm

   npm install @ax-llm/ax
2. 2

   Import ai and ax and create a classifier with your OpenAI API key

3. 3

   Run the classifier by calling forward with an LLM and review text

Things to know

• !Requires an API key from a model provider such as OpenAI or Anthropic to run LLM calls.
• !Multi-language ports (Python, Java, C++, Go, Rust) are generated from the TypeScript source and may lag behind it.

In collections

Topics

FAQ

What is ax?

A TypeScript-first DSPy-style framework for building typed, structured LLM programs with agents, flows, and optimizers, also compiled to Python, Java, C++, Go, and Rust. Ax lets developers describe LLM tasks as typed signatures, either as a short string DSL, a fluent builder, or Standard Schema validators such as Zod, Valibot, and ArkType. Outputs are parsed and validated into typed values, with retries on validation failure. A single provider-name switch selects among many hosted and local model backends, including OpenAI, Anthropic, Google Gemini, Ollama, and OpenAI-compatible endpoints.

Is ax free to use? What license does it have?

ax is open source under the Apache-2.0 license. Check the license terms before using it in commercial products.

Is ax still maintained?

Actively maintained. The last commit to ax was on Nov 6, 2026.

What can I use ax for?

Extracting structured data from emails, tickets, or documents into typed objects Building TypeScript applications that call LLMs with validated outputs Creating multi-step LLM pipelines with branching and retry logic Tuning prompts automatically against a labeled evaluation set

How do I install ax?

Install the TypeScript package from npm: npm install @ax-llm/ax Import ai and ax and create a classifier with your OpenAI API key Run the classifier by calling forward with an LLM and review text

Where can I get ax?

The source code and installation instructions are on GitHub: https://github.com/ax-llm/ax