A string to slug converter turns messy, human-readable text into the clean, lowercase, hyphen-separated format search engines and web frameworks expect in a URL path. Type or paste any title into the box above and the tool strips accents, removes punctuation, and joins the words with hyphens — live, as you type — so you always know exactly what your final URL will look like before you publish.
Consistent, readable URLs are a small detail that compounds over time, and it's the same attention to detail Arb Digital applies across every site we build, blog post we publish, and product page we launch for clients.
What This String to Slug Converter Does
"Slugifying" a string means transforming it into a URL-safe identifier: everything lowercase, spaces and punctuation replaced with a single separator character, accented letters normalized to their plain ASCII equivalents, and any character that isn't a letter, number, or the chosen separator removed entirely. This tool runs that full pipeline in your browser using JavaScript's built-in Unicode normalization, so "Café Menu & Prices — 2026 Édition!" becomes `cafe-menu-prices-2026-edition` without you touching a terminal or writing a regular expression yourself.
You can choose a hyphen or underscore as the separator, cap the result at a maximum length so long titles don't produce unreasonably long URLs, and toggle forced lowercasing off if you specifically need to preserve case for a non-URL use case like a variable name or file identifier.
How to Use It
- Paste your text — a blog post title, product name, or any raw string — into the input field.
- Pick a separator. Hyphens are the standard choice for public-facing URLs; underscores are sometimes used for internal identifiers or filenames.
- Set a max length if you want to cap long titles at a sensible URL length, commonly 50–60 characters for SEO-friendly slugs.
- Copy the result and use it as your URL path, CMS slug field, or filename.
- Re-run it any time your title changes — the slug updates instantly as you edit the input.
How the Conversion Works
The core transformation happens in a few deterministic steps. First, the string is Unicode-normalized using the NFD (Normalization Form Canonical Decomposition) method, which splits accented characters like "é" into a base letter ("e") plus a separate combining accent mark. Stripping those combining marks with a regular expression leaves plain ASCII letters behind — "é" becomes "e," "ü" becomes "u," and so on. This is the same normalization approach documented in the Unicode Standard Annex #15 on normalization forms, which underlies how most modern slug libraries handle international text.
After accent stripping, the string is lowercased, non-alphanumeric characters are replaced with the chosen separator, and consecutive separators are collapsed into one so you never end up with `double--hyphens` or a trailing hyphen at the end of the slug. If a max length is set, the tool truncates at the nearest complete word boundary where possible, rather than cutting a word in half mid-token.
Why Slug Formatting Matters for SEO
Search engines use the words in a URL as a ranking signal, though a modest one compared to titles and content. A URL like `/best-running-shoes-2026/` gives both users and crawlers an immediate, readable signal about the page's topic before they even click. A URL like `/index.php?p=4821` or one full of unencoded spaces and special characters (`%20`, `%C3%A9`) communicates nothing and looks untrustworthy in a search result or a shared link. Clean slugs also tend to get clicked more often — users scanning search results react to readable URLs the same way they react to a clear headline.
Beyond search, clean slugs matter for consistency across a codebase: they're commonly used as database keys, CMS routes, file names, and cache keys, so a predictable, collision-resistant format saves real engineering time compared to handling special characters ad hoc in every system that touches the string.
Choosing Between Hyphens and Underscores
Google's own documentation on URL structure has long recommended hyphens over underscores because Google's indexing treats a hyphen as a word separator (`digital-marketing` is read as two words) while historically it has not reliably treated an underscore the same way (`digital_marketing` risked being read as one token). Most CMS platforms, static site generators, and e-commerce systems default to hyphens for exactly this reason. Underscores still have valid uses — programming identifiers, filenames on systems that treat hyphens specially, or internal database keys — which is why this tool supports both.
- Use hyphens for anything public-facing: blog URLs, product pages, category pages.
- Use underscores only for internal identifiers where hyphen has special meaning (some shell scripts, some legacy systems).
- Never mix both separators in the same slug — pick one and stay consistent site-wide.
Arb Digital handles the full SEO structure — clean slugs, internal linking, sitemaps, and schema — as part of every website and content project we build.
Our Services All Free ToolsCommon Mistakes to Avoid
- Leaving accented characters unconverted, which can render as `%C3%A9`-style encoded gibberish in some browsers and shared links.
- Allowing consecutive hyphens (`--`) to slip through, which looks broken and can confuse some URL parsers.
- Changing a page's slug after it's indexed without setting up a 301 redirect from the old URL, which breaks inbound links and loses accumulated SEO value.
- Making slugs too long — a 150-character slug crammed with every keyword is harder to read and share than a concise, targeted one.
- Including stop words like "a," "the," and "of" unnecessarily, when trimming them keeps the slug tighter without losing meaning.
Related Free Tools From Arb Digital
Pair this with the Open Graph Tag Generator when publishing new pages, the JSON to XML Converter for data exports, and the Cron Expression Generator for scheduling site jobs. Browse the full free online tools hub for more.
What Actually Makes a Good URL Slug
A slug is the human-readable tail of a URL — the best-running-shoes in example.com/best-running-shoes — and a good one is quietly doing SEO and usability work at the same time. Search engines read words in the URL as a mild ranking and relevance signal, and just as importantly, a clean descriptive slug tells a human what the page is before they click, which lifts click-through from search results and makes links shareable. Compare /best-running-shoes with /product?id=48213&cat=7: one is memorable and trustworthy, the other is opaque and easy to mistype.
The conventions that make a slug good are consistent across the web: lowercase everything (URLs can be case-sensitive on some servers, and mixed case invites duplicate-content confusion), use hyphens rather than underscores to separate words because search engines treat hyphens as spaces but underscores as joiners, drop stop words and filler when they add nothing, and keep it reasonably short so the key terms are front-loaded. The generator above applies these rules automatically, turning a raw title into a slug that is tidy, keyword-focused and safe to publish.
Accents, Unicode and the Duplicate-Slug Problem
The trickiest part of slug generation is non-English text. A title like "Café Münchén" contains accented characters that, left raw, get percent-encoded into ugly, unreadable URLs (Caf%C3%A9). The common fix is transliteration — normalising the text and stripping diacritics so é becomes e and ü becomes u, yielding cafe-munchen. This keeps URLs ASCII-clean and portable, though for some languages you may deliberately keep native characters when your audience expects them; there is a genuine trade-off between readability for your users and universal compatibility.
The operational gotcha is uniqueness. Two different posts titled "Introduction" both slugify to introduction, and a URL can only point to one page — so real systems append a differentiator (introduction-2) or a category prefix to keep slugs distinct, and they never silently change a published slug, because doing so breaks every existing link and shared bookmark unless you add a redirect. Generate the slug once at publish time, store it, guarantee it is unique, and treat it as permanent. That discipline keeps your URLs clean today and stops them turning into a graveyard of broken links tomorrow.
Slugs, Redirects and Changing URLs Safely
The most expensive slug mistake is treating a published URL as editable. Once a page is live, its slug is baked into every link others have made to it, every social share, every bookmark, and the search engine index. Change /old-title to /better-title without a plan and all of those links now hit a 404, you lose the accumulated ranking equity of the old URL, and returning visitors get an error instead of your content. This is why mature content systems generate the slug once and then leave it frozen even if the article's headline is later reworded.
When a URL genuinely must change — a rebrand, a restructure, a fixed typo in a high-traffic page — the safe pattern is a 301 permanent redirect from the old slug to the new one. A 301 passes the large majority of the old page's ranking signals to the new URL and transparently forwards any human or crawler who follows an old link, so nothing breaks and little SEO value is lost. Keep a redirect map as part of your site's plumbing, generate clean slugs up front with a tool like this so you rarely need to change them, and when you do, redirect rather than delete. That discipline is the difference between a site whose link equity compounds over years and one that quietly leaks it every time someone edits a title.
Frequently Asked Questions
A slug is the lowercase, hyphen-separated portion of a URL that identifies a specific page, typically derived from its title, such as /best-running-shoes-2026/.
Hyphens are the standard recommendation for public URLs because search engines reliably treat them as word separators; underscores are better reserved for internal identifiers.
It uses Unicode NFD normalization to split each accented letter into its base character and accent mark, then strips the accent mark, leaving plain ASCII behind.
There's no hard limit, but keeping slugs under roughly 60 characters is a common best practice for readability and full display in search results.
The old URL will 404 unless you set up a 301 redirect to the new slug, so existing links and search rankings are preserved.
Yes, it runs entirely in your browser with no sign-up, no character limits, and no data ever sent to a server.
