How to Create SEO-Friendly URL Slugs

Quick Answer

A good URL slug is short, descriptive, lowercase, and stable. Use hyphens between words, keep only the terms that help identify the page, and normalize accented text before slug generation.

What a Slug Should Do

A slug should make the URL readable to humans while staying easy to manage in your CMS or application. It should communicate the page topic clearly without turning into a full sentence or a dump of every keyword variation.

Rules for SEO-Friendly Slugs

• Use lowercase consistently
• Use hyphens, not underscores, for public page URLs
• Keep the slug descriptive but compact
• Remove punctuation and unstable decorative text
• Normalize accented characters before transliteration
• Do not keep dates or update markers unless they matter long term
• Aim for 3-5 words that capture the page topic

Hyphen vs Underscore

Maximum Slug Length

There is no strict character limit, but practical guidelines exist. Keep slugs under 60-70 characters. Longer slugs get truncated in search results and are harder to share. More importantly, every word in the slug should earn its place. If removing a word does not change the meaning, remove it.

When to Remove Stop Words

Remove stop words when they add no meaning, but keep them if dropping them makes the slug awkward or ambiguous. The goal is not maximum compression. The goal is a readable and stable identifier.

Internationalization and Transliteration

Slugs must work in URLs, which means they should contain only ASCII letters, digits, and hyphens. Non-ASCII text requires transliteration: converting characters from other scripts into ASCII equivalents.

Accented Latin Characters

Normalize to NFD (decomposed form) first, then strip the combining diacritical marks. This converts characters like cafe to cafe reliably.

CJK Characters (Chinese, Japanese, Korean)

CJK characters do not transliterate to ASCII in a meaningful way without a romanization library. Options include:

• Use pinyin for Chinese (e.g., a library like pinyin in Python or pinyin-pro in JavaScript)
• Use romaji for Japanese (Hepburn romanization)
• Use revised romanization for Korean
• Alternatively, use a numeric ID or hash as the slug and rely on the page title for readability

Arabic and Cyrillic

Both scripts have established transliteration tables. Use a library like transliterate (JavaScript) or text-unidecode (Python) that maps each character to its closest ASCII equivalent. Always test the output: automated transliteration can produce awkward or misleading results for some words.

Accents, Unicode, and Imported Titles

If your titles contain accented characters or come from mixed systems, normalize the text before slug generation. This reduces inconsistent output and makes transliteration more stable. See the Unicode normalization guide if you are dealing with NFC vs NFD problems.

CMS-Specific Advice

WordPress

WordPress auto-generates slugs from post titles but does not handle CJK text well by default. Install a transliteration plugin for non-Latin scripts. To edit a slug, use the "Permalink" field in the post editor. Avoid changing slugs after publication unless you set up redirects.

Next.js and File-Based Routing

In Next.js, the slug is the filename or folder name in the app/ or pages/ directory. Use kebab-case for folder and file names. For dynamic slugs from a database, sanitize at the data layer before passing to generateStaticParams() or getStaticPaths().

Custom CMS Systems

Build slug generation into your content creation API. Validate that every slug is unique within its URL path, enforce lowercase and hyphen-only rules at the database level, and store the slug as a separate indexed column rather than deriving it at render time.

Redirect Strategy When Slugs Change

Changing a published slug breaks existing links, bookmarks, and search engine rankings. If you must change a slug, always set up a 301 (permanent) redirect from the old URL to the new one.

• 301 redirect: Tells search engines the page has permanently moved. Link equity transfers to the new URL over time.
• Never use 302: A 302 (temporary) redirect tells search engines the old URL might come back, so they may not transfer ranking signals.
• Keep a redirect map: Maintain a table of old-slug to new-slug mappings. In a CMS, store the history of previous slugs for each page and auto-redirect any old slug to the current one.
• Batch changes: If you are changing slug conventions across many pages, do it in one deployment with all redirects in place simultaneously.

Slug Stability and Versioning

A stable slug is one that does not need to change when the content is updated. Design slugs for longevity:

• Do not include the year unless the content is genuinely time-specific (e.g., annual reports).
• Do not include version numbers in the slug. Use /api-authentication not /api-authentication-v2.
• Avoid including the author name, category hierarchy, or other metadata that might change.
• If you need versioned content, use a separate URL parameter or path segment (/docs/v2/authentication) rather than embedding versions in the slug itself.

Programmatic Slug Generation

JavaScript

function slugify(text) {
  return text
    .normalize("NFD")                   // decompose accents
    .replace(/[\u0300-\u036f]/g, "")    // strip diacritical marks
    .toLowerCase()
    .trim()
    .replace(/[^a-z0-9\s-]/g, "")      // remove non-alphanumeric chars
    .replace(/[\s_]+/g, "-")            // spaces and underscores to hyphens
    .replace(/-+/g, "-")               // collapse multiple hyphens
    .replace(/^-|-$/g, "");            // trim leading/trailing hyphens
}

// slugify("Cafe Expose: A Developer's Guide!")
// => "cafe-expose-a-developers-guide"

Python

import re
import unicodedata

def slugify(text):
    text = unicodedata.normalize("NFD", text)
    text = text.encode("ascii", "ignore").decode("ascii")
    text = text.lower().strip()
    text = re.sub(r"[^a-z0-9\s-]", "", text)
    text = re.sub(r"[\s_]+", "-", text)
    text = re.sub(r"-+", "-", text)
    return text.strip("-")

# slugify("Cafe Expose: A Developer's Guide!")
# => "cafe-expose-a-developers-guide"

Common Slug Mistakes

• Keeping punctuation and update markers such as (updated) without need
• Using percent-encoded titles instead of real slugs
• Changing slugs too often after publishing
• Removing too many words and losing meaning
• Skipping cleanup when titles contain hidden Unicode characters
• Including query parameters or fragments in what should be a path-only slug

FAQ

Related Tools

• URL Slug Generator to generate clean slugs quickly
• URL Encoder / Decoder for URL escaping, which is a different job than slug creation

Related Guides

• Unicode Normalization for accent and normalization edge cases
• Hidden Unicode Characters for invisible-character cleanup