Aspen

Building or debugging REST APIs on a Mac and frustrated by bloated tools that require accounts, send your data to the cloud, or cost money? Aspen is a free, no-login API testing app built exclusively for macOS that puts privacy first. All operations run locally on your machine — nothing is stored externally. What makes Aspen stand out beyond privacy is its built-in AI assistance: it can generate data models, OpenAPI Specs, and integration code to help you move faster without leaving the app. Clean, lightweight, and genuinely useful for developers who care about both their workflow and their data security.