URL Slug Generator

How it works

The conversion is a short pipeline, and the order of the steps matters.

First, optional lowercasing. Then German umlaut expansion, if enabled — this has to happen before the next step, because once a diaeresis has been stripped the information needed to write "ue" is gone.

Then a small table of hard cases: ß, æ, œ, ø, ł, đ and a few others. These cannot be handled automatically because they are not an ASCII letter with a mark attached; they are separate letters in their own right, and mapping them takes a human decision.

Then the general case: the string is normalized to NFD, which decomposes a character like é into a plain e followed by a combining acute accent. Every character in Unicode's Mark category is then deleted, leaving the base letters behind. One rule handles the large majority of Latin diacritics without a per-letter table.

Finally, every run of characters that is neither a letter nor a number becomes a single separator, repeated separators collapse, and — if a maximum length is set — the result is cut at the last separator before the limit rather than mid-word.

Why the truncation rule matters

Cutting a slug at a fixed character count is the kind of shortcut that looks fine in testing and produces embarrassing URLs in production. A title truncated at 60 characters might end /how-to-build-a-community-around-your-newslett, which is worse than the shorter, whole-word version.

Trimming back to the last separator costs a few characters and always yields something that reads as finished. Where no separator exists inside the limit — a single very long word — the hard cut is used, because there is no better option available.

When you'd use this

The single-title case is the obvious one: you have a headline, you need the URL.

The batch case is where it earns its place. Planning a content cluster usually starts as a list of thirty or forty working titles in a spreadsheet. Converting those to slugs one at a time is tedious enough that people skip it, publish with whatever their CMS auto-generated, and end up with a site whose URLs are inconsistent — some with stop words, some without, some truncated, some enormous. Converting the whole column in one paste makes consistency the easy option rather than the disciplined one.

A note on permanence

A slug is the most permanent decision in a piece of content. The title can be rewritten, the copy can be updated, the images can be replaced — none of that disturbs anything pointing at the page. The slug cannot be changed without breaking every existing link to it.

That is worth thirty seconds of thought before publishing, and it is the real argument for generating slugs deliberately rather than accepting whatever a CMS derives from the first draft of a headline.