API Testing in VS Code Using `api.http` (REST Client) — A Practical Guide for Experienced Developers

If you’ve spent years using tools like Postman, you already understand the value of structured API testing, collections, environments, and documentation. But as projects mature, you may start wanting something: Lightweight Version-controlled Close to the codebase Zero context switching That’s where the REST Client extension in VS Code with .http files becomes a serious alternative. For a 4–5 year experienced developer, this isn’t about replacing Postman. It’s about: Keeping API examples in Git Reducing tool overhead Treating API calls as documentation Making backend repos self-testable This guide walks you from installation to advanced environment setup, including two major issues most developers hit: --- vs ### request separation and JSON parsing errors Why rest-client.environment.json sometimes doesn’t work and how .vscode/settings.json solved it 1️⃣ Why Use api.http Instead of Postman? For experienced developers, the real advantages are: ✅ Version Control Friendly .http files live i