This is the Postman Collection SDK, a JavaScript library that provides a complete object model for Postman Collections (v2.1 format). It enables developers to create, manipulate, serialize, and deserialize collections, items, requests, responses, variables, and other HTTP-related constructs. The library is used internally by Postman's own tools (e.g., Newman, Postman app) and by third-party integrations. It features a class hierarchy rooted in PropertyBase, with PropertyList for generic indexed lists, variable substitution via SuperString, dynamic variable generation (faker-based), URL matching patterns, content-type detection, and mutation tracking. The codebase is well-tested (100% unit test coverage enforced) and includes both Node.js and browser support. While the core architecture is clean and modular, some dependencies are outdated (lodash 4.18.1, file-type 3.9.0) and there are deprecated API surfaces maintained for backward compatibility. The SDK is actively maintained with frequent releases and CI/CD pipelines.