What is the difference between dependencies and dev_dependencies in pubspec.yaml?

Overview

In Flutter/Dart,

pubspec.yaml

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  dependencies

  — Packages needed at runtime (included in the final app build)
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  dev_dependencies

  — Packages needed only during development (NOT included in production)

dependencies

Packages listed under

dependencies

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# pubspec.yaml
dependencies:
  flutter:
    sdk: flutter

  # State management
  provider: ^6.1.2
  flutter_bloc: ^8.1.6

  # Networking
  http: ^1.2.2
  dio: ^5.7.0

  # Local storage
  shared_preferences: ^2.3.3
  sqflite: ^2.4.1

  # UI
  cached_network_image: ^3.4.1
  flutter_svg: ^2.0.15

  # Navigation
  go_router: ^14.6.2

  # Firebase
  firebase_core: ^3.8.1
  firebase_auth: ^5.3.4

dev_dependencies

Packages listed under

dev_dependencies

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# pubspec.yaml
dev_dependencies:
  flutter_test:
    sdk: flutter

  # Testing
  mockito: ^5.4.4
  bloc_test: ^9.1.7
  integration_test:
    sdk: flutter

  # Code generation
  build_runner: ^2.4.13
  json_serializable: ^6.8.0
  freezed: ^2.5.7

  # Linting
  flutter_lints: ^5.0.0
  very_good_analysis: ^6.0.0

  # Launcher icons & splash screen
  flutter_launcher_icons: ^0.14.2
  flutter_native_splash: ^2.4.3

Key Differences

dependencies

dev_dependencies

lib/

test/

The Rule

The official Dart documentation states:

If the dependency is imported from something in your

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lib/

or

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bin/

directories, it must be a regular dependency. If it's only imported from

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test/

or

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example/

directories, it can and should be a

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dev_dependency

.

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// ✅ In lib/services/api_service.dart — uses regular dependency
import 'package:dio/dio.dart'; // dio must be in dependencies

// ✅ In test/services/api_service_test.dart — uses dev_dependency
import 'package:mockito/mockito.dart'; // mockito can be in dev_dependencies

Common Mistakes

Mistake 1: Putting test packages in dependencies

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# ❌ Wrong — mockito is only used in tests
dependencies:
  mockito: ^5.4.4

# ✅ Correct — keep test packages in dev_dependencies
dev_dependencies:
  mockito: ^5.4.4

Mistake 2: Putting code generation in dependencies

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# ❌ Wrong — build_runner is a dev tool, not runtime
dependencies:
  build_runner: ^2.4.13

# ✅ Correct
dev_dependencies:
  build_runner: ^2.4.13
  json_serializable: ^6.8.0

Mistake 3: Putting runtime packages in dev_dependencies

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# ❌ Wrong — provider is used in lib/ code
dev_dependencies:
  provider: ^6.1.2

# ✅ Correct — provider is needed at runtime
dependencies:
  provider: ^6.1.2

Special Case: Code Generation Packages

Code generation packages have a split setup:

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dependencies:
  json_annotation: ^4.9.0    # Runtime annotations (used in lib/)
  freezed_annotation: ^2.4.4 # Runtime annotations (used in lib/)

dev_dependencies:
  json_serializable: ^6.8.0  # Generator (only runs during dev)
  freezed: ^2.5.7            # Generator (only runs during dev)
  build_runner: ^2.4.13      # Build tool (only runs during dev)

Key Insight: Keeping dev-only packages in

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dev_dependencies

reduces your production app size and avoids shipping unnecessary code to users. Always ask: "Does my app need this package to run?" If not, it belongs in

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dev_dependencies

.