Pubspec

pubspec is the metadata file used by Dart and Flutter projects to describe a package, its dependencies, and related configuration. The file, named pubspec.yaml, is located at the project root and is managed by the Dart package manager (pub) and tooling. It informs pub how to resolve and fetch dependencies and provides information relevant to publishing the package.

The file is written in YAML and typically includes fields such as name, version, and description to identify the package and its purpose. It also records environment constraints under environment (for example, sdk: ">=2.17.0 <3.0.0"). Dependencies and dev_dependencies specify the libraries the project relies on, with version constraints. A dependency_overrides section can force specific versions when necessary. For Flutter projects, a top-level flutter key can define assets, fonts, and other Flutter-specific settings. Other common fields include homepage or repository for links, publish_to to control publishing to pub.dev, and documentation.

When changes are made to pubspec.yaml, developers run pub get (or dart pub get, or flutter pub get) to fetch the declared dependencies. The pubspec.lock file is generated to lock exact versions used, ensuring reproducible builds. The file also plays a role in publishing: the publish_to field can designate a publishing target, with "https://pub.dev" as the default for public packages.

Example (illustrative, not exhaustive):

name: my_package

version: 1.0.0

description: A sample Dart package

environment:

sdk: ">=2.17.0 <3.0.0"

dependencies:

http: ^0.13.0

dev_dependencies:

test: ^1.16.0

flutter:

uses-material-design: true

Pubspec serves as the central source of package metadata and dependency configuration for Dart and Flutter projects.