The slug is the part of a URL that comes after the domain name and identifies a specific page. In “yoursite.com/how-to-create-seo-friendly-urls,” the slug is “how-to-create-seo-friendly-urls.” It looks simple, and the rules for creating a good one are not complicated, but getting it right manually every single time is tedious enough that most developers and content writers reach for a slug generator to do the conversion automatically rather than doing it by hand.
What a URL slug is and why it matters for SEO
A URL slug is a human-readable identifier that tells both users and search engines what a page is about before they even click on it. Search engines analyze URL structure as one of the signals they use to understand and rank content. A clean, keyword-relevant slug is a small but real SEO signal, and it is one of the easiest to get right since it requires no technical setup once a good workflow is in place.
More practically, clean slugs make URLs easier to share, easier to remember, and more trustworthy when they appear as text in a social media post or a messaging app preview. A URL that ends in “/how-to-bake-sourdough-bread” communicates content and intent immediately. A URL that ends in “/p?id=4892” or “/blog/post-1” communicates nothing and is considerably less likely to earn a click from someone who is not already familiar with the site.
Google has explicitly stated that descriptive, keyword-relevant URLs are preferred, and that URLs should be simple and readable. While the direct ranking weight of URL structure is relatively small compared to content quality and backlinks, its indirect effects, on click-through rate, on anchor text when others link to the page, and on the overall coherence of a site's information architecture, are worth taking seriously.
The rules for a good slug
Lowercase only. URLs are technically case-sensitive on most web servers, which means “/Blog/Post” and “/blog/post” can be treated as two different pages. This creates duplicate content issues that hurt SEO. Using all lowercase for every slug eliminates this problem entirely.
Hyphens, not underscores. Google treats hyphens as word separators in URLs, meaning “seo-friendly-url” is read as three separate words. Google treats underscores as word joiners, meaning “seo_friendly_url” is read as one long compound word. For SEO purposes, hyphens are almost always the right choice for slug separators. Underscores have their place in certain technical contexts and in some development frameworks, but for content URLs targeting search traffic, hyphens consistently perform better.
No special characters. Characters like @, #, %, &, ?, and = have reserved meanings in URLs and need to be percent-encoded if they appear in a path, which produces the ugly %40, %23, %25 sequences that make URLs unreadable. Apostrophes, quotation marks, and other punctuation cause similar problems. A good slug contains only letters, numbers, and the chosen separator character.
Keep it short. The general best practice is to keep slugs under 60 characters. Shorter slugs are easier to read, easier to share, and display fully in most search result snippets without truncation. They are also generally more memorable. A slug that is simply “seo-friendly-urls” is better than one that is “how-to-create-perfectly-optimized-seo-friendly-urls-for-your-blog.” The extra words add length without adding meaningful information.
Include the target keyword. The slug should contain the primary keyword for the page, ideally near the beginning. A blog post targeting “sourdough bread recipe” should have a slug like “sourdough-bread-recipe” or “sourdough-bread-recipe-beginners,” not “my-first-bread-post” or “baking-2026.”
Stop words and whether to remove them
Stop words are common words that carry little semantic weight on their own: “the,” “a,” “an,” “and,” “of,” “in,” “for,” “is,” and similar words that appear in almost every sentence but do not themselves signal topic or intent.
The argument for removing stop words from slugs is that they add length without adding SEO value, since search engines largely ignore them in queries. A title like “The Best Ways to Improve Your SEO in 2026” might produce a slug like “the-best-ways-to-improve-your-seo-in-2026” with stop words, or “best-ways-improve-seo-2026” without them. The shorter version is tighter and contains exactly the words that matter for the search.
The argument against automatic stop word removal is that it can sometimes produce slugs that are grammatically odd or ambiguous when the stop words are load-bearing in context. “How to Get a Job” without stop words becomes “get-job,” which is shorter but reads slightly strangely compared to “how-to-get-a-job,” which is immediately clear. This tool makes stop word removal optional rather than mandatory, so you can choose based on the specific title you are working with.
Where slugs are used and who needs a slug generator
Blog posts and articles are the most common context where slug generators get used. A WordPress installation, for example, generates a slug automatically from the post title, but the automatic slug often needs adjustment because it includes stop words, is too long, or does not match the primary keyword target precisely. Generating a clean slug here and pasting it directly into the permalink field in WordPress removes the need to manually fix whatever the CMS generated.
E-commerce product pages have the same need at much larger scale. A product catalog with thousands of items, each needing a clean, unique, keyword-relevant slug, cannot realistically be managed manually. Even with automated slug generation built into the platform, there are always edge cases, product names with special characters, names in multiple languages, names that are too long, where manual intervention and a reliable slug generator become necessary.
Developers building content management systems, static site generators, or any web application that creates URL paths from user-supplied text need slug generation logic built in. The function itself is straightforward, but writing and testing it correctly across edge cases, accented characters, apostrophes in contractions, ampersands, consecutive hyphens, leading and trailing hyphens, takes time. Using this tool to verify expected slug output during development is faster than running a test suite every time a new edge case surfaces.
Content teams working in headless CMS environments or in tools that do not auto-generate slugs need to produce clean slugs manually for every piece of content they publish. A slug generator that works in the browser with no setup is considerably faster than a developer writing a one-off script or a content writer trying to remember and apply all the slug rules correctly by hand every time.
Hyphens versus underscores: the definitive answer
This question comes up enough that it is worth addressing directly. For URLs intended to rank in search results, use hyphens. Google has confirmed this repeatedly, and it is the consistent recommendation from every major SEO resource because of how Google treats the two characters differently when parsing URL structure.
Underscores are not wrong in an absolute sense. They are used routinely in Python file naming conventions, in certain database table naming conventions, and in some URL patterns where they carry specific technical meaning. If you are generating slugs for a URL structure defined by a framework or specification that uses underscores, use underscores. If you are generating slugs for public-facing content URLs with no pre-existing convention, use hyphens.
Handling accented and non-ASCII characters
Titles in languages that use accented characters, like French, Spanish, German, or Portuguese, need their accented letters converted to their nearest ASCII equivalents in a slug. The é in “référence” becomes “e,” the ñ in “año” becomes “n,” and the ü in “über” becomes “u.” This process, called transliteration, ensures the slug contains only safe ASCII characters that work reliably in every browser and server environment without encoding.
This tool handles transliteration automatically using Unicode normalization, so titles with accented characters produce clean ASCII slugs without any manual character replacement. If you also need to check the character count of a generated slug before using it, the word counter shows both character and word counts for any text you paste into it.
Changing slugs on existing pages
One thing worth knowing before changing slugs on pages that are already live and indexed: updating a slug changes the URL of the page, and any existing inbound links, bookmarks, or indexed URLs pointing to the old slug will break unless a redirect is set up. A 301 redirect from the old URL to the new one passes the link equity and tells search engines the page has permanently moved. Without that redirect, you lose any rankings and backlink value the old URL had accumulated.
The practical advice is to get the slug right before publishing when possible, because changing it later requires managing redirects. For new content, using a slug generator to produce a clean, keyword-relevant slug before the first publish is the lowest effort, highest reward slug optimization you can do.