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cURL Guide for HTTP Methods

· 3 min read
Anand Raja
Anand Raja
Senior Software Engineer

cURL is a command-line tool used to interact with APIs and perform HTTP requests. The name cURL is derived from "Client for URLs" or simply "command URL". Below is a guide on how to use cURL for common HTTP methods.

1. GET Request​

Used to retrieve data from a server.

curl -X GET https://api.example.com/resource

With Query Parameters:

curl -X GET "https://api.example.com/resource?key=value&key2=value2"

With Headers:

curl -X GET https://api.example.com/resource \
     -H "Authorization: Bearer YOUR_TOKEN" \
     -H "Content-Type: application/json"

You can use curl without the -X option. By default, curl uses the GET method if no HTTP method is specified.

curl http://localhost:11434/api/models

This will perform a GET request to the specified URL.

2. POST Request​

Used to send data to a server to create a resource.

curl -X POST https://api.example.com/resource \
     -d '{"key":"value", "key2":"value2"}' \
     -H "Content-Type: application/json"

With Form Data:

curl -X POST https://api.example.com/resource \
     -F "key=value" \
     -F "file=@/path/to/file.txt"

With Headers:

curl -X POST https://api.example.com/resource \
     -H "Authorization: Bearer YOUR_TOKEN" \
     -H "Content-Type: application/json" \
     -d '{"key":"value"}'

You can omit -X POST if you include data using the -d option, as curl automatically switches to POST when data is provided:

curl http://localhost:11434/api/generate \
     -d '{ "model": "llama3.2", "prompt": "Tell me a fun fact about space." }'

3. PUT Request​

Used to update an existing resource.

curl -X PUT https://api.example.com/resource/123 \
     -d '{"key":"new_value"}' \
     -H "Content-Type: application/json"

With Headers:

curl -X PUT https://api.example.com/resource/123 \
     -H "Authorization: Bearer YOUR_TOKEN" \
     -H "Content-Type: application/json" \
     -d '{"key":"updated_value"}'

4. DELETE Request​

Used to delete a resource.

curl -X DELETE https://api.example.com/resource/123

With Headers:

curl -X DELETE https://api.example.com/resource/123 \
     -H "Authorization: Bearer YOUR_TOKEN"

For methods like DELETE, you must explicitly specify the method using -X because curl does not assume DELETE by default

5. PATCH Request​

Used to partially update a resource.

curl -X PATCH https://api.example.com/resource/123 \
     -d '{"key":"partial_update"}' \
     -H "Content-Type: application/json"

6. OPTIONS Request​

Used to retrieve supported HTTP methods for a resource.

curl -X OPTIONS https://api.example.com/resource

7. HEAD Request​

Used to retrieve headers without the response body.

curl -X HEAD https://api.example.com/resource

8. Sending Authentication​

Basic Authentication:

curl -u username:password https://api.example.com/resource

Bearer Token:

curl -X GET https://api.example.com/resource \
     -H "Authorization: Bearer YOUR_TOKEN"

9. Saving Response to a File​

curl -X GET https://api.example.com/resource -o response.json

10. Verbose Mode (Debugging)​

curl -X GET https://api.example.com/resource -v

11. Custom Headers​

curl -X GET https://api.example.com/resource \
     -H "Custom-Header: CustomValue"

12. Follow Redirects​

curl -L https://api.example.com/resource

13. Sending Data from a File​

curl -X POST https://api.example.com/resource \
     -d @data.json \
     -H "Content-Type: application/json"

14. Combining Multiple Options​

curl -X POST https://api.example.com/resource \
     -H "Authorization: Bearer YOUR_TOKEN" \
     -H "Content-Type: application/json" \
     -d '{"key":"value"}' \
     -o response.json -v

Summary​

  • GET: No need for -X, as it's the default method.
  • POST: Automatically used when -d or --data is provided.
  • Other Methods (PUT, DELETE, etc.): Require -X to specify the method explicitly.