URL Converter

Double encoding happens when URLs are encoded multiple times, turning "%20" into "%2520". This occurs when encoded URLs pass through multiple encoding layers without proper validation.

• Check if input is already encoded
• Decode before re-encoding
• Use framework-specific URL builders
• Test the entire data flow end-to-end

URLEncoder/URLDecoder are designed for HTML form encoding (application/x-www-form-urlencoded), not full URLs. Using them on entire URLs corrupts the URL structure and breaks navigation.

• Only encode query parameters and path segments
• Preserve URL structure (://, /, ?, &)
• Use appropriate encoding for each URL component
• Test with browser developer tools

International characters require proper UTF-8 encoding for URL safety. Without specifying character encoding, non-ASCII characters can break URLs or cause security issues.

• Always specify UTF-8 encoding
• Test with emoji and special characters
• Handle accented characters properly
• Consider punycode for domain names

Unencoded user input in URLs can lead to injection attacks. Malicious users can manipulate URLs by adding fragments (#) or query parameters to control requests and access unauthorized data.

• Always encode user-generated URL components
• Validate URL parameters before processing
• Use allowlists for expected characters
• Implement proper input sanitization

Reserved characters like &, ?, =, and # have special meanings in URLs. Encoding them incorrectly breaks URL parsing, while not encoding them in data causes parameter confusion.

• Encode only in data values, not URL structure
• & separates parameters - don't encode in structure
• ? starts query string - preserve its function
• = connects parameter names to values

Different URL components have different encoding requirements. Path segments, query parameters, and fragments each need specific handling to maintain URL functionality while ensuring data safety.

• Path segments: Encode spaces and special chars
• Query params: Encode values but not structure
• Fragments: Rarely need encoding
• Userinfo: Always encode credentials

Most modern web frameworks automatically decode URL parameters before passing them to your application. Understanding this prevents double-decoding and helps debug URL-related issues.

• Test framework behavior with encoded data
• Don't manually decode if framework does it
• Check decoded vs raw parameter values
• Handle special cases where needed

Production-ready URL handling requires systematic encoding, validation, testing, and monitoring. Implement proper error handling and use established libraries for consistent results.

• Use built-in language URL builders
• Validate URLs before external requests
• Log encoding/decoding operations
• Test with real-world special characters