How to Automatically Generate SEO-Friendly URLs in PHP

A URL like /post.php?id=4821 tells a search engine and a user absolutely nothing. A URL like /blog/seo-friendly-urls-php tells them everything before the page even loads. Turning the first into the second is a single PHP function, and this guide gives you the complete, working code.

SEO-friendly URLs are automatically generated in PHP by converting a title or heading into a clean, lowercase, hyphen-separated slug, stripping special characters, transliterating accented letters, and checking the result against existing records to guarantee it stays unique.

We covered the writing side of this in our SEO-friendly blog posts guide. This article handles the technical half: the actual PHP that turns a title into a clean, working URL automatically.

What Turning a Title Into a Slug Actually Looks Like

Step 1: The Core Slugify Function

This single function handles transliteration, lowercasing, and cleanup in one pass, using PHP's built-in iconv function.

<?php
function slugify(string $text, string $separator = '-'): string {
    // Transliterate accented and Unicode characters to plain ASCII
    $text = iconv('UTF-8', 'ASCII//TRANSLIT//IGNORE', $text);

    // Lowercase everything
    $text = strtolower($text);

    // Replace anything that isn't a letter or number with the separator
    $text = preg_replace('/[^a-z0-9]+/', $separator, $text);

    // Trim separators from both ends
    $text = trim($text, $separator);

    // Collapse repeated separators into a single one
    $text = preg_replace('/' . preg_quote($separator, '/') . '+/', $separator, $text);

    return $text;
}

echo slugify('10 Content Writing Mistakes That Reduce Rankings!');
// Output: 10-content-writing-mistakes-that-reduce-rankings

A complete, working slugify function using PHP's built-in iconv transliteration

Step 2: Guaranteeing Uniqueness Against a Database

Two posts titled the same thing will otherwise generate identical slugs. This version checks the database and appends a number if needed.

<?php
function generateUniqueSlug(PDO $pdo, string $title, ?int $excludeId = null): string {
    $baseSlug = slugify($title);
    $slug = $baseSlug;
    $counter = 2;

    while (slugExists($pdo, $slug, $excludeId)) {
        $slug = $baseSlug . '-' . $counter;
        $counter++;
    }
    return $slug;
}

function slugExists(PDO $pdo, string $slug, ?int $excludeId = null): bool {
    $sql = "SELECT COUNT(*) FROM posts WHERE slug = :slug";
    $params = ['slug' => $slug];

    if ($excludeId !== null) {
        $sql .= " AND id != :id";
        $params['id'] = $excludeId;
    }

    $stmt = $pdo->prepare($sql);
    $stmt->execute($params);
    return (int) $stmt->fetchColumn() > 0;
}

Appends -2, -3, and so on until an unused slug is found; excludeId prevents false positives when editing an existing post

Step 3: Putting It Together on Save

<?php
$title = $_POST['title'];
$slug = generateUniqueSlug($pdo, $title);

$stmt = $pdo->prepare("INSERT INTO posts (title, slug, created_at) VALUES (:title, :slug, NOW())");
$stmt->execute(['title' => $title, 'slug' => $slug]);

A complete insert flow: title comes in, a guaranteed-unique SEO-friendly URL goes into the database

Step 4: Making the URL Actually Work

Generating the slug is only half the job. The server needs to route that clean URL to the right script.

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^blog/([a-z0-9-]+)/?$ blog-post.php?slug=$1 [L,QSA]

location /blog/ {
    rewrite ^/blog/([a-z0-9-]+)/?$ /blog-post.php?slug=$1 last;
}

Live Slug Generator

Type a title below to see the exact SEO-friendly URL the PHP function above would generate.

Why SEO-Friendly URLs Matter Beyond Rankings

According to Achromatic's guide to SEO-friendly slugs, a clean URL improves click-through rate directly, since users can see what a page is about before ever clicking the search result.

SEO-friendly URLs also make internal linking easier to manage. A URL like /blog/seo-friendly-urls-php is self-documenting in code, on a sitemap, or in analytics reports, unlike an opaque numeric ID that requires a database lookup to understand.

Transliteration Options Beyond the Basic Function

According to Slug Generator's guide to creating SEO-friendly URL slugs in PHP, PHP's intl extension offers ICU-based transliteration for cases where iconv's simpler approach does not cover a specific language well enough.

According to Our Code World's guide to creating URL slugs properly in PHP, a custom character map is another option for teams needing precise control over how specific accented or Cyrillic characters convert, beyond what a generic transliteration function provides by default.

Testing Your SEO-Friendly URL Setup End to End

According to PHP's official preg_replace documentation, testing the slugify function against edge cases, titles with numbers, punctuation, and mixed languages, catches formatting issues before they reach production.

Once the PHP side generates a correct SEO-friendly URL, confirm the rewrite rule actually resolves it by visiting the new URL directly in a browser, not just linking to it internally.

According to Edureka's community discussion on generating SEO-friendly URL slugs, a working rewrite rule returns the correct page with a 200 status; a broken one returns a 404 even though the slug itself was generated correctly.

Common Mistakes to Avoid

Handling Slug Changes Safely

According to DevToolHub's 2026 URL slug best practices guide, once a URL is indexed, has backlinks, or has been shared, changing the slug breaks every one of those existing references unless a redirect is put in place.

According to Rich Dev Tools' guide to URL slug rules and SEO impact, a simple redirects table mapping old slugs to new ones, checked before a 404 response, handles this cleanly without manual .htaccess edits for every single change.

FAQs on Generating SEO-Friendly URLs in PHP