Postman Collections are based on the open source collection format, which defines a structure for organizing API requests and modeling API workflows. The format is portable, machine and human readable, and can be used to generate client and server SDKs, documentation, and mock servers. The current version of Postman uses schema 3.0.0. Previous Postman schemas are available on the Postman Schemas site.
The collections schema 3.0.0 defines a collection with multiple YAML files organized on disk, so humans, AI agents, and automation tools can read, diff, review, and safely change collections in the same way as source code.
Any folder can serve as a collection root, with requests stored as *.request.yaml files and supporting assets living in reserved .resources/ directories. Each request has a sibling <request-name>.resources directory containing its examples and scripts subdirectories, while collection- and folder-level metadata lives in optional definition.yaml files.
Collections schema version 3.0.0 enforces filename-safe naming rules with normalization guidance, case-insensitive uniqueness, and mandatory forward-slash paths. The .yml extension is accepted as a parser alias, but .yaml is required for authoring output, and explicit path-resolution rules keep request resources scoped within their canonical directory.
Ordering and sorting are handled by numeric fractional indexes to sort folders, requests, and examples. Examples and scripts are the initial normative resource types, but new resource directories can be added under <request-name>.resources without breaking existing naming rules. A shared model with an explicit type field keeps the format protocol-independent and future-proof.