schemalint 1.0.1

OpenAI and Anthropic structured-output APIs accept only a strict subset of JSON Schema. Ship a schema with an unsupported keyword, a missing required entry, or the wrong additionalProperties, and the API rejects it — in production, at request time, as a 400.

schemalint catches those errors at build time, checked against the exact provider rules, so a bad schema fails your CI instead of your users' requests.

Install

# npm / bun — adds the `schemalint` command to your project
npm install -D @1nder-labs/schemalint

# Rust
cargo install schemalint

# Python
pip install schemalint

Quick start

Check a schema against OpenAI's structured-output rules:

schemalint check --profile openai.so.2026-04-30 schema.json

error[OAI-K-allOf]: keyword 'allOf' is not supported by openai.so.2026-04-30
  --> schema.json

1 issue found (1 error, 0 warnings) across 1 schema

Check a whole directory, for both providers at once:

schemalint check \
  --profile openai.so.2026-04-30 \
  --profile anthropic.so.2026-04-30 \
  schemas/

Lint Zod and Pydantic directly

Schemas live in your code, not in .json files? schemalint reads them straight from your Zod or Pydantic definitions — no manual JSON Schema export, no second package to install.

// package.json
{
  "scripts": { "lint:schemas": "schemalint check-node" },
  "schemalint": {
    "profiles": ["openai.so.2026-04-30"],
    "include": ["src/**/*.ts"]
  }
}

npm run lint:schemas        # Zod  → check-node
schemalint check-python     # Pydantic → check-python

What it catches

Unsupported keywords (allOf, oneOf, not, unsupported formats, …) per provider
Missing required entries and additionalProperties: false mistakes
Invalid root shapes, unsupported $ref patterns, and enum / nesting limits
Size and depth limits that otherwise only surface as a runtime 400

Providers

Provider	Profile
OpenAI Structured Outputs	`openai.so.2026-04-30`
Anthropic Structured Outputs	`anthropic.so.2026-04-30`

In CI

schemalint exits non-zero on errors, so it fails the build before a broken schema ever ships:

- run: npx schemalint check --profile openai.so.2026-04-30 schemas/

Pick the output format that fits your pipeline:

schemalint check --format json   --profile openai.so.2026-04-30 schema.json   # machine-readable
schemalint check --format sarif  --profile openai.so.2026-04-30 schema.json   # code scanning
schemalint check --format gha    --profile openai.so.2026-04-30 schema.json   # GitHub Actions annotations

Exit code	Meaning
`0`	No errors
`1`	Schema, parse, or read errors
`2`	Could not write the output file

Documentation

Contributing

Bug reports, new rules, and provider profiles are all welcome — see CONTRIBUTING.md and CODE_OF_CONDUCT.md.

Security

Found a vulnerability? Please report it privately — see SECURITY.md.

License

Dual-licensed under MIT or Apache-2.0, at your option.