URL Rewrite Tester

About URL Rewrite Tester

This URL rewrite tester validates regex-based rewrite rules by testing pattern matching and replacement transformations before deploying to Apache, Nginx, or IIS servers.

It is useful for testing mod_rewrite rules, Nginx location blocks, IIS URL Rewrite configurations, debugging complex regex patterns, verifying capture group extraction, preventing production URL breaks, and ensuring clean URL routing works correctly before server configuration changes.

How URL Rewrite Rules Work

Rewrite rules follow a three-step process:

1. Pattern Matching: The regex pattern is tested against the source URL path
2. Capture Extraction: Parentheses groups (capture groups) extract matching values
3. Replacement: The target string uses $1, $2, etc. to insert captured values

Example Rewrite Rule:
Source URL:  /blog/123
Pattern:     ^/blog/(\d+)$
Target:      /posts?id=$1

Step 1: Match pattern against /blog/123 ✓
Step 2: Capture group (\d+) extracts "123"
Step 3: Replace $1 with "123" → /posts?id=123

Result: /blog/123 → /posts?id=123

Common Rewrite Pattern Examples

Regex Pattern Reference

Apache mod_rewrite Example

# Enable rewrite engine
RewriteEngine On

# Clean URL for blog posts
RewriteRule ^blog/([0-9]+)$ /post.php?id=$1 [L,QSA]

# Clean URL for user profiles
RewriteRule ^user/([a-zA-Z0-9_-]+)$ /profile.php?username=$1 [L,QSA]

# Remove .html extension
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}\.html -f
RewriteRule ^(.*)$ $1.html [L]

# Force HTTPS
RewriteCond %{HTTPS} off
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

Nginx Rewrite Example

# Enable rewrite in server block
server {
    listen 80;
    server_name example.com;

    # Blog post clean URLs
    rewrite ^/blog/([0-9]+)$ /post.php?id=$1 last;

    # User profile URLs
    rewrite ^/user/([a-zA-Z0-9_-]+)$ /profile.php?username=$1 last;

    # Remove .html extension
    location ~ ^(.+)\.html$ {
        if (-f $document_root$1) {
            rewrite ^(.+)\.html$ $1 last;
        }
    }

    # Force HTTPS
    if ($scheme = http) {
        return 301 https://$server_name$request_uri;
    }
}

Common Use Cases

• Clean URLs: Convert /page.php?id=123 to /page/123 for better SEO
• Migration: Redirect old URL structures to new ones during site redesign
• Canonicalization: Force www vs non-www, HTTP vs HTTPS, trailing slashes
• Language Routing: Route /en/, /es/, /fr/ to appropriate language handlers
• API Versioning: Route /api/v1/users to version-specific handlers
• Legacy Support: Maintain old URLs while migrating to new structure

Rewrite vs Redirect

Testing Checklist

Before deploying rewrite rules:

□ Pattern matches expected URLs
□ Pattern does NOT match unrelated URLs
□ Capture groups extract correct values
□ Replacement produces valid target URLs
□ No infinite rewrite loops
□ Query parameters preserved (QSA flag)
□ Special characters properly escaped
□ Case sensitivity is correct
□ Anchors (^ and $) used appropriately
□ Tested with edge cases (empty, special chars)