Build Your Own Postman Alternative: A Terminal-First API Testing CLI

Build Your Own Postman Alternative: A Terminal-First API Testing CLI GUI-based API testing tools like Postman served us well for years, but a growing number of developers are trading their point-and-click workflows for something leaner: terminal-first API testing. The reasons are compelling — CLI tools integrate naturally with version control, play well with CI/CD pipelines, consume fewer resources, and keep developers in the flow state that context-switching to a GUI application inevitably breaks. In this tutorial, we will build httpcli , a fully functional terminal-first API testing tool that reads .http files (the same format used by VS Code's REST Client extension), supports variables, environment management, request chaining, authentication helpers, response diffing, and syntax-highlighted output. By the end, you will have a tool that handles 90% of what Postman does — from your terminal. Why Developers Are Moving to CLI-Based API Testing The shift is not just about preference. It