---
title: Seamline Toolkit
description: Breaking-change detection and typed environment contracts for Node.js. Two MIT-licensed, ESM-only tools for API and environment validation.
url: https://pr-1-8289d63b6330.thally.app/
---

# Seamline Toolkit

Breaking-change detection and typed environment contracts for Node.js. Two MIT-licensed, ESM-only tools for API and environment validation.

The Seamline Toolkit contains two complementary products for maintaining contract integrity across your application:

- **Specdiff**: Detects breaking changes in JSON Schema and OpenAPI documents. Compare versions, enforce compatibility policies, and integrate with CI/CD pipelines.
- **Envlock**: Validates environment variables against a typed contract. Declare what your app needs once, then validate, type, document, and diff it everywhere.

#### [Specdiff](/specdiff/overview)

#### [Envlock](/envlock/overview)

## Requirements

Both products are **v0.1.0**, **MIT-licensed**, and require:

- Node.js **>=22**
- **ESM only** (no CommonJS)

Start by choosing a product or jump straight to the [Quickstart](/quickstart).