Should I use hyphens or underscores in a URL slug?

Hyphens. Google treats hyphens as word separators but does not reliably treat underscores the same way, making hyphens the standard for SEO-friendly URLs.

Should a slug be all lowercase?

Yes, lowercase is the standard convention for URL slugs, since some servers treat uppercase and lowercase letters as different, which can cause duplicate-content or broken-link issues.

What happens to punctuation like apostrophes in a slug?

Punctuation is typically stripped out entirely rather than encoded, since encoded punctuation makes URLs harder to read and share.

Slug Generator

Turn any text into a clean, URL-friendly slug — live preview as you type.

Enter your text

Max length 0 = no limit

Preserve numbers Lowercase

Start typing above to see your slug preview

How to Use

Type or paste any text into the input field — slugs update instantly as you type.
Set a Max length to truncate slugs to a specific character limit (0 = unlimited).
Toggle Preserve numbers to keep or strip numeric characters.
Click Copy next to any slug variant to copy it to the clipboard.

Slugs are used in URLs, file names, and identifiers. Special characters, accents, and punctuation are automatically removed or transliterated.

About this Slug Generator

A URL slug is the readable part of a web address that identifies a specific page — in "example.com/best-pizza-recipes," the slug is "best-pizza-recipes." Slugs need to follow specific formatting rules that a title or headline typically doesn't.

What makes a good slug

Lowercase only: URLs are conventionally lowercase to avoid confusion, since some servers treat capitalization as meaningful
Hyphens, not spaces: spaces are not valid in URLs and get encoded as %20, which looks messy; hyphens are the standard word separator
No special characters: punctuation like apostrophes, colons, and ampersands are stripped or replaced, since they can break URL parsing or need encoding
Short and descriptive: a slug should convey the page topic without unnecessary filler words

Hyphens vs. underscores

Google has confirmed that hyphens are treated as word separators in URLs, while underscores are not — a search engine reads "best-pizza-recipes" as three separate words but may read "best_pizza_recipes" as one run-together term. This makes hyphens the standard choice for SEO-friendly slugs.

Example

The title "10 Best Pizza Recipes You'll Ever Make!" converts to the slug "10-best-pizza-recipes-youll-ever-make" — lowercase, spaces replaced with hyphens, and the apostrophe and exclamation point removed.