cURL Commands for Beginners: Testing APIs from the Command Line

cURL is an indispensable developer tool installed by default on macOS, Linux, and modern Windows terminals. It allows developers, DevOps engineers, and QA testers to inspect HTTP headers, benchmark server response times, and debug REST APIs directly from the command line.

Core cURL Commands and Flags

1. Basic HTTP GET Request

curl https://api.example.com/users

2. Follow Redirects (-L)

By default, curl stops at HTTP 301/302 redirects. Use -L (or --location) to follow redirects to the final destination:

curl -L https://example.com

3. Inspect Response Headers Only (-I)

Quickly check HTTP status codes (200, 301, 404, 500) and caching headers:

curl -I https://www.aiwithab.site

4. Send a POST Request with JSON Data

curl -X POST https://api.example.com/items \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_TOKEN" \
  -d '{"name": "New Tool", "category": "developer"}'

5. Silent Mode with Progress Bar Disabled (-s)

Suppress download metering when piping output to JSON formatters:

curl -s https://api.example.com/data | jq .

Format and inspect JSON payloads from your API responses using our JSON Formatter and validate inputs with Regex Tester.