How It Works
Download
Get Siren for Windows, macOS, or Linux
Create Requests
Build HTTP requests with an intuitive interface
Save & Organize
Keep collections and history stored locally
Everything You Need
A complete toolkit for API testing
Request History
Track and replay past requests
Collections
Organize requests into folders
Variables
Parameterize requests with reusable variables
Light & Dark Mode
Choose your preferred theme
Local Storage
Your data stays on your machine
Plugin System
Extend functionality with plugins
Powerful HTTP Client
Make requests to your favorite HTTP endpoints and test your local WebApi projects with ease. Keep a history of your requests and save collections of related calls for quick access.
Make HTTP requests to any endpoint
Request history tracking
Save and organize collections
Built for Developers
Built by developers, for developers. Siren focuses on a clean, distraction-free experience with no accounts, no cloud sync requirements, and no friction.
Light & Dark Mode
Local machine persistence
No Sign Up Required
Why Choose Siren?
See how Siren compares to other tools
| Feature | Siren | Postman | Insomnia |
|---|---|---|---|
| Free Forever | Limited |
Limited | |
| No Account Required | |||
| Local Data Storage | Cloud-first |
Cloud-first | |
| Open Source | MIT |
Partial | |
| Lightweight | Moderate |
Built with Modern Tech
Siren leverages cutting-edge .NET technologies for a native cross-platform experience. Built with Blazor Hybrid and Photino for lighter weight, faster performance than a typical Electron cross-platform app.
Blazor Hybrid & .NET 10
Photino to leverage native webviews
MudBlazor with Material 3 & ShadCn inspirations
Frequently Asked Questions
Everything you need to know about Siren
Is Siren really free?
Yes! Siren is 100% free and open source under the MIT license. There's no premium tier, no feature gating, and no hidden costs. You get the full application with all features.
Do I need to create an account?
No account is required. Siren works entirely locally on your machine. Just download, install, and start making requests immediately.
Where is my data stored?
All your data—including request history, collections, and settings—is stored locally on your machine. Nothing is sent to the cloud, and you have full control over your data.
What platforms are supported?
Siren is available for Windows 10+, macOS 11+, and Linux (Ubuntu, Fedora, and other major distributions). All builds are signed for your security.
Can I contribute to Siren?
Absolutely! Siren is open source on GitHub. We welcome contributions of all kinds—bug reports, feature requests, documentation improvements, and code contributions.
Free & Open Source
Siren is completely free and open source under the MIT license. Inspect the code, contribute improvements, or fork it for your own needs.
MIT Licensed on GitHub
Community Contributions Welcome
Full Source Code Available
