Swift SDK Comparison

This repository demonstrates how different SDK generator tools produce Swift SDKs when given the same OpenAPI specification.
The goal is to provide Swift developers with an easy, side-by-side comparison of SDK output quality, style, and ergonomics.

Generators Compared

We generate Swift SDKs using the following tools:

• Apple’s Swift OpenAPI Generator
• Fern’s Swift OpenAPI Generator

API Specification

All SDKs in this repository are generated from the Travel Train API specification, provided by our friends at Bump.sh.
Using a single consistent spec ensures the comparisons highlight generator differences rather than spec design.

Purpose

• Highlight differences in code style, dependencies, and developer experience.
• Provide an apples-to-apples comparison by using the same API specification as input.
• Help Swift developers and API platform teams evaluate which SDK generator best fits their needs.

Contents

Each directory contains a generated Swift SDK from one of the tools above.
Typical comparison points include:

• Client initialization and configuration (authentication, base URL setup)
• API method signatures and ergonomics (parameter handling, response types)
• External dependencies (runtime frameworks, package footprint)
• Generated code size and complexity (file count, maintainability)
• Error handling patterns (error types, throwing vs. Result types)
• Swift language feature usage (async/await, structured concurrency, modern Swift idioms)
• Type safety and nullability (optional handling, type-safe enums)
• Documentation and code comments (inline docs, usage examples)

How to Use

1. Browse the directories for each SDK generator.
2. Review the generated code and note differences in:
   • Readability and maintainability
   • Use of Swift language features
   • Package manager setup (e.g., Swift Package Manager compatibility)

Contributing

If you’d like to add another SDK generator for comparison:

1. Generate a Swift SDK using the same OpenAPI specification.
2. Create a new directory named after the generator.
3. Include a short README.md inside describing the tool and version used.
4. Open a pull request.

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This repository is affiliated with Fern and not Apple or openapi-generator. It is intended as a neutral comparison resource for Swift developers.