llm-abi

One schema. Every model.

Documentation

Guide

Give llm-abi one type or schema. Get the provider-safe schema back. Four labels, no percentage.

Give llm-abi one TypeScript type or JSON Schema. It returns the schema each provider will actually accept, and what changed.

It does not call a model. Put result.schema on the SDK you already use. Compatibility is four labels — never a percentage.

npm install llm-abi

import { compile } from "llm-abi";

const result = compile(schema, "anthropic");

if (result.compatibility === "unsupported") {
  throw new Error("This schema cannot be represented on Anthropic.");
}

const checked = result.validate(modelJson);
if (!checked.ok) {
  throw new Error("The model output failed the original schema.");
}

How to read the result

Result Meaning What you do
lossless The provider schema keeps the written meaning Send result.schema
runtime-safe Some constraints were stripped Send it, then call result.validate
lossy The rewrite changed meaning (oneOf → anyOf, …) Decide whether that change is OK
unsupported The construct cannot be represented Change the schema or the target

result.validate always checks the original schema, not the lowered one. If Anthropic moved minimum into a description, age: -1 still fails validation.

Three questions, three functions

You want to know Call
Can this schema be represented on this provider? compile / check
Can this model + endpoint + tools + reasoning combination be sent? checkRequest
Can this contract hold on a local or self-hosted runtime? checkDeployment

Do not fold request or runtime rules into compile(). compile(schema, "qwen") is Alibaba Model Studio, not a laptop Qwen GGUF.

Next

  • Playground — paste a type or schema. Compilation stays in the browser.
  • API — compile, check, checkRequest, checkDeployment
  • CLI — npx llm-abi check schema.json
  • Profiles — built-in targets and evidence
  • Requests — checkRequest for model, endpoint, tools, and reasoning
  • Local runtimes — LM Studio, Ollama, llama.cpp, vLLM, SGLang
  • Guarantees — what is deterministic, and what is not
  • Architecture — Schema ABI, Request ABI, and Runtime ABI