Essential curl commands for HTTP requests, API testing, and file transfers.
Command-line tool for making HTTP requests and transferring data.
# Simple GET request
curl https://api.example.com
# Save output to file
curl https://example.com -o output.html
curl https://example.com/file.zip -O # Use remote filename
# Follow redirects
curl -L https://example.com
# Show response headers
curl -i https://example.com
# Show only headers
curl -I https://example.com
# Verbose output (debugging)
curl -v https://example.com
# POST with data
curl -X POST https://api.example.com/users \
-d "name=John&[email protected]"
# POST JSON data
curl -X POST https://api.example.com/users \
-H "Content-Type: application/json" \
-d '{"name":"John","email":"[email protected]"}'
# POST from file
curl -X POST https://api.example.com/users \
-H "Content-Type: application/json" \
-d @data.json
# Form upload
curl -X POST https://api.example.com/upload \
-F "[email protected]" \
-F "description=My document"
# PUT request
curl -X PUT https://api.example.com/users/1 \
-H "Content-Type: application/json" \
-d '{"name":"Jane"}'
# DELETE request
curl -X DELETE https://api.example.com/users/1
# PATCH request
curl -X PATCH https://api.example.com/users/1 \
-H "Content-Type: application/json" \
-d '{"email":"[email protected]"}'
# Add custom header
curl -H "User-Agent: MyApp/1.0" https://example.com
# Multiple headers
curl -H "Accept: application/json" \
-H "Authorization: Bearer token123" \
https://api.example.com
# Basic auth
curl -u username:password https://api.example.com
# Bearer token
curl -H "Authorization: Bearer YOUR_TOKEN" \
https://api.example.com
# API key in header
curl -H "X-API-Key: your_api_key" \
https://api.example.com
# API key in URL
curl "https://api.example.com?api_key=your_key"
# Connection timeout (seconds)
curl --connect-timeout 10 https://example.com
# Max time for entire operation
curl --max-time 30 https://example.com
# Retry on failure
curl --retry 3 https://example.com
# Retry delay
curl --retry 3 --retry-delay 5 https://example.com
# Send cookies
curl -b "session=abc123" https://example.com
# Save cookies to file
curl -c cookies.txt https://example.com
# Load cookies from file
curl -b cookies.txt https://example.com
# Both save and load
curl -b cookies.txt -c cookies.txt https://example.com
# Use HTTP proxy
curl -x http://proxy.example.com:8080 https://api.example.com
# With proxy authentication
curl -x http://proxy:8080 -U user:pass https://api.example.com
# SOCKS proxy
curl --socks5 127.0.0.1:1080 https://api.example.com
# Ignore SSL certificate errors (not recommended for production)
curl -k https://self-signed.example.com
# Use specific SSL version
curl --tlsv1.2 https://example.com
# Use client certificate
curl --cert client.crt --key client.key https://example.com
# Show SSL handshake details
curl -v https://example.com 2>&1 | grep -i ssl
# Silent mode (no progress bar)
curl -s https://api.example.com
# Show only HTTP status code
curl -s -o /dev/null -w "%{http_code}" https://example.com
# Custom output format
curl -w "\nTime: %{time_total}s\nStatus: %{http_code}\n" \
https://example.com
# Pretty print JSON (with jq)
curl -s https://api.example.com | jq '.'
# Download specific byte range
curl -r 0-1000 https://example.com/large-file.zip
# Resume download
curl -C - -O https://example.com/large-file.zip
# Download file
curl -O https://example.com/file.zip
# Download with custom name
curl -o myfile.zip https://example.com/file.zip
# Download multiple files
curl -O https://example.com/file1.zip \
-O https://example.com/file2.zip
# Resume interrupted download
curl -C - -O https://example.com/large-file.zip
# FTP upload
curl -T file.txt ftp://ftp.example.com/upload/
# HTTP PUT upload
curl -T file.txt https://example.com/upload
# Form file upload
curl -F "[email protected]" https://example.com/upload
# Test REST API
curl -X GET https://api.example.com/users
curl -X GET https://api.example.com/users/1
curl -X POST https://api.example.com/users -d @user.json
curl -X PUT https://api.example.com/users/1 -d @updated.json
curl -X DELETE https://api.example.com/users/1
# Test with verbose output
curl -v -X POST https://api.example.com/login \
-H "Content-Type: application/json" \
-d '{"username":"test","password":"pass"}'
# Measure request time
curl -w "Total time: %{time_total}s\n" https://example.com
# Detailed timing
curl -w "\nDNS: %{time_namelookup}s\nConnect: %{time_connect}s\nTLS: %{time_appconnect}s\nTransfer: %{time_starttransfer}s\nTotal: %{time_total}s\n" \
-o /dev/null -s https://example.com
# Show request and response headers
curl -v https://api.example.com
# Trace request
curl --trace-ascii trace.txt https://api.example.com
# Include response headers in output
curl -i https://api.example.com
Quick JSON API test:
curl -s https://api.github.com/users/octocat | jq '{name, bio, followers}'
Download with progress bar:
curl -# -O https://example.com/large-file.zip
POST JSON and extract field:
curl -s -X POST https://api.example.com/login \
-H "Content-Type: application/json" \
-d '{"user":"test","pass":"secret"}' | jq -r '.token'
Check if URL is accessible:
if curl -s --head --fail https://example.com > /dev/null; then
echo "Site is up"
else
echo "Site is down"
fi
Parallel downloads:
for i in {1..10}; do
curl -O https://example.com/file$i.jpg &
done
wait
-X: HTTP method (GET, POST, PUT, DELETE, etc.)-d: Data to send (POST/PUT)-H: Custom header-o: Output file-O: Save with remote filename-L: Follow redirects-i: Include headers in output-I: Headers only-v: Verbose output-s: Silent mode-S: Show errors even in silent mode-f: Fail silently on HTTP errors-k: Insecure (ignore SSL)-u: Basic authentication-F: Multipart form data-b: Send cookies-c: Save cookies-w: Custom output format-s in scripts to suppress progress bar-sS for silent but show errors-L for redirects (e.g., shortened URLs)-v for debuggingjq to process JSON responses--config for complex reusable requestsOfficial docs: https://curl.se/docs/
Manual: man curl
HTTP methods: https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods