DevRef
CLI

curl Cheatsheet

Quick reference for curl commands including GET, POST, headers, authentication, cookies, file upload, and debugging options.

Basic Requests

CommandDescription
curl https://example.comSimple GET request
curl -o file.html https://example.comSave to file
curl -O https://example.com/file.zipSave with remote filename
curl -L https://example.comFollow redirects
curl -s https://example.comSilent mode (no progress)
curl -S https://example.comShow errors in silent mode
curl -sS https://example.comSilent but show errors

HTTP Methods

# GET (default)
curl https://api.example.com/users

# POST
curl -X POST https://api.example.com/users

# PUT
curl -X PUT https://api.example.com/users/1

# PATCH
curl -X PATCH https://api.example.com/users/1

# DELETE
curl -X DELETE https://api.example.com/users/1

# HEAD (headers only)
curl -I https://example.com

Sending Data

# POST with form data
curl -d "name=Alice&age=30" https://api.example.com/users

# POST with JSON
curl -X POST https://api.example.com/users \
  -H "Content-Type: application/json" \
  -d '{"name": "Alice", "age": 30}'

# POST with JSON from file
curl -X POST https://api.example.com/users \
  -H "Content-Type: application/json" \
  -d @data.json

# URL-encoded data (explicit)
curl --data-urlencode "name=Alice Smith" https://api.example.com/users

# Send raw data from stdin
echo '{"key":"value"}' | curl -d @- https://api.example.com/data

Headers

# Set custom header
curl -H "Authorization: Bearer token123" https://api.example.com

# Multiple headers
curl -H "Accept: application/json" \
     -H "X-Custom: value" \
     https://api.example.com

# Show response headers
curl -i https://example.com

# Show only response headers
curl -I https://example.com

Authentication

# Basic auth
curl -u username:password https://api.example.com

# Bearer token
curl -H "Authorization: Bearer token123" https://api.example.com

# API key in header
curl -H "X-API-Key: key123" https://api.example.com

# Netrc file
curl -n https://api.example.com     # Uses ~/.netrc

Cookies

# 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

# Save and send cookies (session persistence)
curl -c cookies.txt -b cookies.txt https://example.com

File Upload

# Upload file (multipart form)
curl -F "file=@photo.jpg" https://api.example.com/upload

# Upload with field name and filename
curl -F "avatar=@photo.jpg;filename=profile.jpg" https://api.example.com/upload

# Multiple files
curl -F "file1=@a.txt" -F "file2=@b.txt" https://api.example.com/upload

# Upload with additional form fields
curl -F "file=@photo.jpg" -F "description=My photo" https://api.example.com/upload

# PUT upload (raw)
curl -T file.txt https://api.example.com/files/file.txt

Debugging & Verbose

# Verbose output
curl -v https://example.com

# Extra verbose (includes hex dump)
curl --trace - https://example.com

# Trace to file
curl --trace trace.log https://example.com

# Show timing information
curl -w "time_total: %{time_total}s\n" -o /dev/null -s https://example.com

# Write-out format variables
curl -w "\n%{http_code}\n%{size_download}\n%{time_total}\n" -sS https://example.com

Write-Out Variables

VariableDescription
%{http_code}HTTP status code
%{time_total}Total time in seconds
%{time_connect}Time to connect
%{time_starttransfer}Time to first byte
%{size_download}Downloaded bytes
%{size_upload}Uploaded bytes
%{url_effective}Final URL (after redirects)
%{redirect_url}Redirect URL
%{content_type}Content-Type header
%{num_redirects}Number of redirects

SSL / TLS

# Skip certificate verification (insecure)
curl -k https://self-signed.example.com

# Use specific CA certificate
curl --cacert /path/to/ca.pem https://example.com

# Client certificate
curl --cert client.pem --key client-key.pem https://example.com

Proxy

# HTTP proxy
curl -x http://proxy:8080 https://example.com

# SOCKS5 proxy
curl --socks5 localhost:1080 https://example.com

# Proxy with auth
curl -x http://user:pass@proxy:8080 https://example.com

# No proxy for specific hosts
curl --noproxy "localhost,127.0.0.1" https://example.com

Download

# Download with progress bar
curl -# -O https://example.com/large-file.zip

# Resume interrupted download
curl -C - -O https://example.com/large-file.zip

# Limit download speed
curl --limit-rate 1M -O https://example.com/file.zip

# Timeout
curl --connect-timeout 5 --max-time 30 https://example.com

# Retry
curl --retry 3 --retry-delay 2 https://example.com

Useful Combinations

# Pretty-print JSON response
curl -s https://api.example.com/data | jq .

# POST JSON and pretty-print response
curl -sS -X POST https://api.example.com/data \
  -H "Content-Type: application/json" \
  -d '{"key":"value"}' | jq .

# Download multiple files
curl -O https://example.com/file[1-5].txt

# Check if URL is reachable
curl -sS --head --fail https://example.com > /dev/null && echo "OK" || echo "FAIL"