---
title: "dart_openapi_generator"
description: "Native-Dart OpenAPI 3.x → Dart code generator for Flutter and Dart."
---

Reads a local OpenAPI 3.x spec (YAML or JSON) and generates idiomatic
Dio-based model classes and API client services via `build_runner`. No Mustache.
Generated code looks like a developer wrote it by hand.

## Features

- Generates `final class` model classes with `fromJson`, `toJson`, `copyWith`, `==`, and `hashCode`
- Generates Dart `enum` types with `fromJson`/`toJson` switch expressions
- Generates `sealed class` hierarchies for `oneOf` schemas with a discriminator
- Flattens `allOf` schemas into a single merged class
- Handles `additionalProperties` (typed or untyped)
- Generates Dio-based service classes from OpenAPI paths — one file per tag
- Generates an aggregator client class with static auth-helper factories (Bearer, API key header/query, HTTP Basic)
- Configured via `build.yaml` `options:` — no Dart annotation, no runtime annotation package
- Generated files are tracked in build_runner's own asset graph, so a single `build_runner build` resolves correctly on the first pass — including for downstream builders that import generated types
- Supports OpenAPI 3.0, 3.1, and 3.2 (including `in: querystring` and `additionalOperations`)
- Zero runtime dependencies in the consumer's tree — `dart_openapi_generator` is a dev dependency

## Installation

```yaml title="pubspec.yaml"
dependencies:
  dio: ^5.0.0

dev_dependencies:
  dart_openapi_generator: ^0.2.0
  build_runner: ^2.4.0
```

## Get Started

Follow the [Getting Started guide](/getting-started) to go from zero to a working API client.

See the [Options Reference](/options-reference) for every `build.yaml` option.