Aspen is a free to use, no logging required API testing app for macOS. It is specifically made to meet the needs of testing REST APIs, and with the help of AI, instantly help with integrations by generating data models, OAS and integration code.
Aspen is a free native macOS app for testing REST APIs with a built-in AI assistant and no login required.
- for
- macOS developers who need fast, local REST API testing and AI-assisted integration code.
- pricing
- free
works withmacOSREST APIs
Key features
6 features of Aspen - API Testing for macOS
- Native macOS app — Runs locally on macOS with a super-optimized UI for fast test execution.
- Zero-trust, no data storage — All operations are performed locally; no data is saved or sent to a server.
- No login required — Start testing immediately without creating an account.
- AI Companion Alfred — Generates data models, OpenAPI specs, and integration code directly from the UI.
- Aspen Collections — Organize, import, export, and share API requests; supports Postman file import.
- Instant results — Returns test responses in less than a second.
Use cases
- Quickly test REST endpoints on a Mac without configuring external tools.
- Generate OpenAPI specifications from existing API calls.
- Create integration code snippets for client libraries.
- Share a set of API requests with teammates via Collections.
- Import a Postman collection to continue work in Aspen.
Aspen - API Testing for macOS vs alternatives
| Best for | Local REST API testing with AI assistance | Open-source cross-platform API testing | API composition and backend generation | SDK generation and docs publishing | Support automation |
|---|---|---|---|---|---|
| Pricing | Free | Free | Free | Subscription | Free |
| DevHunt upvotes | 4 | 48 | 38 | 81 | 82 |
| Launched | Apr 2024 | Jan 2023 | Jan 2023 | Jan 2024 | Mar 2024 |
- Aspen - API Testing for macOS vs Firecamp: Firecamp is an open-source Postman alternative that runs cross-platform, while Aspen is macOS-only and focuses on zero-trust local testing.
- Aspen - API Testing for macOS vs WunderGraph: WunderGraph provides API composition and backend generation, whereas Aspen is a lightweight tester with AI assistance.
- Aspen - API Testing for macOS vs Sideko: Sideko generates SDKs and documentation, while Aspen focuses on manual testing and AI-assisted code snippets.
- Aspen - API Testing for macOS vs QueryPal: QueryPal automates support workflows, not API testing; Aspen is dedicated to REST API testing on macOS.
Aspen - API Testing for macOS FAQ
Is Aspen free?+
Yes, Aspen is a free API-testing tool with a forever-free tier.
Do I need to create an account?+
No, Aspen requires no login; you can start testing immediately.
How does Aspen protect my data?+
All operations run locally on your machine and no data is stored or transmitted, following a zero-trust policy.
What AI features does Aspen provide?+
The built-in AI assistant can generate data models, OpenAPI specs, and integration code to speed up development.
Can I share API requests with my team?+
Yes, the Collections feature lets you organize, import, export, and share requests, including imports from Postman.
Summarized by DevHunt from getaspen.io · Sep 28, 2026. Details may change; check the official site.