Harbinger

"The herald of your API's true nature"

A Rust implementation that captures live API responses from Postman collections and automatically generates OpenAPI 3.0 specifications.

This tool runs your Postman collections against your actual API, captures the real responses, and automatically generates an accurate OpenAPI 3.0 spec based on what your API is actually returning. Think of it as a herald announcing the true structure of your API to the world.

Features

• 🦀 Pure Rust - Fast, safe, and efficient
• 🔄 Live Response Capture - Generates specs from actual API responses, not saved examples
• 📦 HAR Export - Saves HTTP Archive files for debugging and analysis i - 🎯 OpenAPI 3.0 - Generates industry-standard OpenAPI specifications
• 🔧 Variable Support - Resolves Postman variables from collections and environments
• 📝 YAML Output - Human-readable OpenAPI spec files
• 🖥️ Desktop Application - Beautiful Tauri-based GUI with file browser, variable manager, and live progress tracking
• 🎨 Professional Icons - Complete icon set for all platforms (Windows, macOS, Linux, iOS, Android)

Desktop Application

Harbinger includes a beautiful desktop application built with Tauri and React. The GUI provides:

• File Browser - Easy Postman collection and environment file selection
• Variable Manager - Edit and manage collection variables with preset templates
• Live Progress - Real-time execution monitoring with request logs
• Results Viewer - Syntax-highlighted spec display with copy and save options
• History Tracking - Keep track of your recent generations
• Dark/Light Mode - Modern UI with theme support

Desktop App Features

• Platform Support: Windows, macOS, Linux
• Native Performance: Tauri provides near-native speed
• Modern UI: Built with React and Tailwind CSS
• Professional Icons: Complete icon set in src-tauri/icons/ including:
  • Windows: .ico and various sizes
  • macOS: .icns format
  • Linux: PNG formats
  • Mobile: Android and iOS app icons
  • Store: App store and Microsoft store logos

Installation

From crates.io (Recommended)

cargo install harbinger

From Source

cargo build --release

The binary will be available at target/release/harbinger (or harbinger.exe on Windows).

Desktop Application

To build and run the desktop application:

cd src-tauri
cargo tauri dev

Usage

Generate OpenAPI Spec (One Command)

Run your collection and generate an OpenAPI spec in one step:

.\target\release\harbinger.exe generate -c collection.json -e environment.json -o openapi-spec.yaml

Just Run Collection (Save HAR)

Run your collection and save the HAR file for later processing:

.\target\release\harbinger.exe run -c collection.json -e environment.json -o api-run.har

Command Options

generate Command

Runs the collection and generates an OpenAPI spec.

• -c, --collection <FILE> - Path to Postman collection JSON file (required)
• -e, --environment <FILE> - Path to Postman environment JSON file (optional)
• -o, --output <FILE> - Output OpenAPI spec file path (default: openapi-spec.yaml)

run Command

Runs the collection and saves the HAR file.

• -c, --collection <FILE> - Path to Postman collection JSON file (required)
• -e, --environment <FILE> - Path to Postman environment JSON file (optional)
• -o, --output <FILE> - Output HAR file path (default: api-run.har)

How It Works

1. Parse Collection: Reads your Postman collection and environment files
2. Resolve Variables: Replaces {{variable}} placeholders with actual values
3. Execute Requests: Runs each request in your collection against your live API
4. Capture Responses: Records all request/response data in HAR format
5. Generate Schema: Analyzes response bodies and infers JSON schemas
6. Build OpenAPI: Creates a complete OpenAPI 3.0 specification

Example Workflow

1. Export your Postman collection as collection.json
2. Export your Postman environment as environment.json
3. Run the generator:

   .\target\release\harbinger.exe generate -c collection.json -e environment.json
   

4. Your OpenAPI spec is saved to openapi-spec.yaml

Exporting from Postman

Export Collection

1. In Postman, click on your collection
2. Click the three dots (⋯) → Export
3. Choose Collection v2.1
4. Save as collection.json

Export Environment

1. In Postman, click the environment dropdown (top right)
2. Click the eye icon (👁️)
3. Click Export next to your environment
4. Save as environment.json

Features Supported

• ✅ GET, POST, PUT, DELETE, PATCH, HEAD, OPTIONS methods
• ✅ Request headers
• ✅ Request body (raw JSON)
• ✅ Variable substitution ({{variable}})
• ✅ Collection variables
• ✅ Environment variables
• ✅ Nested folders
• ✅ JSON schema inference
• ✅ Multiple response status codes

Why Rust?

This is a Rust rewrite inspired by the Newman CLI (Apache 2.0 licensed). Rust provides:

• Performance: Fast execution, low memory usage
• Safety: No runtime errors, memory-safe
• Concurrency: Async/await for efficient API calls
• Portability: Single binary, no dependencies

License

This project is licensed under the Apache License 2.0, matching the original Newman CLI license.

Differences from Newman

While Newman is a full-featured collection runner, this tool focuses specifically on:

1. Running collections to capture live responses
2. Generating OpenAPI specs from those responses

It's optimized for the spec generation workflow rather than being a general-purpose testing tool.