Starlight 0.39 is another update to Astro’s official tool for building documentation sites. It isn’t a release that turns everything upside down. And that’s a good thing. This time the Astro team focused on the things that genuinely matter in day-to-day work: more flexible navigation, small visual fixes and better support for multilingual sites.
If you use Starlight for product documentation, a help centre, a knowledge base or a technical guide, this version can make it easier to keep your content tidy. Especially when the documentation starts to grow and a simple category layout is no longer enough.
What exactly is Starlight?
Starlight is Astro’s official package for creating fast, accessible documentation sites. You can think of it as a ready-made foundation for technical documentation, a help centre, user guides, onboarding guides or an internal knowledge base.
The biggest advantage is simple: you don’t have to build everything from scratch. Starlight gives you a ready-made documentation layout, search, a sidebar, multi-language support, a mobile version, good SEO basics and a sensibly organised structure. On top of that it runs on Astro, so the site can be fast, light and easy to maintain.
It isn’t a tool only for big open-source projects. It works just as well for a company that wants to organise its guides, describe a product, prepare documentation for customers or move knowledge out of PDFs and scattered notes into one clear place.
The most important change: a more flexible sidebar
The biggest new feature in Starlight 0.39 is more flexible generation of links in the side navigation. The sidebar in documentation matters enormously, because it decides whether the user quickly finds the right section or starts wandering around the site.
From the start, Starlight could automatically generate sidebar links based on content directories. That’s convenient, especially when the documentation has many pages. Previously, though, an auto-generated block like that worked more rigidly. Now you can mix it more freely with other types of links.
What does that mean in plain terms? You can have a single group in the navigation where some links are added manually, some are generated automatically from a directory, and some point to external resources. Without workarounds and without artificial hacks.
Why is that useful?
In small documentation the difference can seem cosmetic. You have a few pages, a few categories and it’s all simple. The problem starts later, when the content grows. You add guides, API sections, configuration instructions, guides for different users, “start here” pages, links to the client panel, the repository or technical support.
Then the navigation has to be not just automatic but well organised too. Not everything should drop into the sidebar in the order dictated by the directories. Sometimes you need to add an important page higher up, highlight a support link, combine content from several places or insert an external link alongside local documentation pages.
And that’s exactly where Starlight’s new flexibility makes sense. It gives you more control over the structure without giving up the convenience of auto-generated links.
An example use in documentation
Imagine documentation for a system that has a “Features” section. In that section you want to show one hand-written landing page, then an automatically generated list of pages from a directory, and finally a link to an external help centre.
Previously a layout like that was less natural. In Starlight 0.39 you can do it more cleanly, because auto-generated links can be part of the items array, alongside normal links and external links.
starlight({
sidebar: [
{
label: 'Features',
items: [
'features-overview',
{ autogenerate: { directory: 'features' } },
{ label: 'Support', link: 'https://support.example.com' },
],
},
],
})This is more readable and more predictable. And with larger documentation it really matters, because a sidebar can very quickly become the place where the mess begins.
Styling fixes
The second group of changes is about the look and behaviour of the interface. These aren’t things the user always notices straight away, but small details like this often decide whether documentation is comfortable to use.
Starlight 0.39 improved the spacing in nested lists, among other things. It sounds unexciting, but in documentation lists are everywhere: step-by-step instructions, requirements, configuration options, parameters, setting variants. If elements like that have too little spacing or blur into one another, the text becomes tiring.
The stability of the sidebar when expanding and collapsing groups was also improved. This is about reducing the layout shifts that appeared in some situations when the height changed and the page scrolled. A detail, supposedly. But in documentation, the interface “jumping about” is more of a nuisance than you might think.
Better support for multilingual sites
Starlight has always leaned heavily into multilingual documentation. Version 0.39 brings further improvements in this area, particularly important for projects that have several language versions and want to do well in search engines.
The most important change is better alternate links for SEO, including support for x-default. That’s a signal to search engines about which version of the page should be treated as the default when there’s no better language match for the user.
For an ordinary business website that may sound technical, but for international documentation it matters a lot. If a user comes from a country or language for which you don’t have a separate version, the search engine should know where best to send them.
Better readability for Chinese and Japanese
The update also brings improved text layout for documentation in Chinese and Japanese. Here Starlight uses the CSS property text-autospace, which helps automatically add spacing between CJK characters and characters outside that set.
For an English-speaking user this won’t be the most noticeable change. But for global projects that run documentation in several languages, improvements like this are important. Documentation should be readable not just in English.
i18next update
Starlight 0.39 also updates i18next, the library responsible for part of the localisation machinery. Moving from version 23 to 26 is a technical step, but an important one for keeping the project in good health.
Up-to-date dependencies mean fewer problems in the future, better compatibility and easier maintenance of the documentation. It isn’t a feature you’ll show a client in a screenshot, but on a longer-running project these things simply need to be kept under control.
How to update Starlight?
Updating an existing Starlight site can be done through Astro’s official upgrade tool. The simplest command looks like this:
npx @astrojs/upgradeThis command updates Starlight, Astro and the integrations you use. After updating it’s worth running the build, checking the site locally and making sure the documentation works correctly. On larger projects it’s also a good idea to review the changelog, especially if the sidebar configuration was heavily customised.
Does Starlight 0.39 change anything for businesses?
For businesses, the most important thing is that Starlight is maturing as a documentation tool. It’s no longer just a nice template for a few pages of instructions. It’s an increasingly complete system for building an organised, fast and accessible knowledge base.
If a business has a technical product, a SaaS app, software, an internal system or a complex service, good documentation can take a lot of weight off support. The user finds an answer faster, the team gets fewer repetitive questions, and customer onboarding is calmer.
Starlight is a good fit for uses like this, because it doesn’t need a heavy CMS. The content can be kept in files, versioned alongside the code and deployed like a normal Astro project. For technical teams that’s often more convenient than clicking around an admin panel.
Documentation as part of the customer experience
Documentation is often treated as an afterthought. First you build the site, then the product, then the panel, and the instructions “will get written one day”. The result is predictable: users ask about the same things, support answers by hand, and the knowledge is scattered across emails, PDFs and Slack messages.
Well-made documentation solves that problem. It doesn’t replace human contact, but it gives the customer a first place to look. If it’s fast, clear and well organised, it genuinely improves how the whole service is perceived.
Starlight 0.39 heads in exactly that direction. It improves not so much the “wow” factor as the everyday work with documentation. And that’s often more important than another big feature.
When is it worth using Starlight?
Starlight makes sense where content needs to be organised, easy to search and comfortable to read. It works especially well for technical documentation, product guides, a knowledge base, API documentation, onboarding guides and materials for customers or staff.
It’s a good choice if the documentation needs to be fast, light and you don’t want to build it on WordPress with yet another theme and a set of plugins. Astro and Starlight offer a more technical but also more controlled approach. Fewer random dependencies, more order.
Starlight 0.39 — a small update, but in the right direction
Starlight 0.39 doesn’t try to start a revolution. It’s more of a calm refinement of a tool that’s already well suited to creating documentation. A more flexible sidebar makes it easier to organise larger content, the styling fixes improve readability, and the changes to multi-language support help projects that go beyond a single language.
For a business owner the most important takeaway is simple: if you need documentation, a help centre or a knowledge base, you don’t have to reach for a heavy CMS straight away. Starlight on Astro can give you a faster, cleaner and calmer solution.
Documentation on Astro in practice
At Astrofy we build fast sites on Astro and Tailwind, but the same approach works well for documentation too. If you have a product, a technical service, a B2B system or an internal knowledge base, you can build a separate, light documentation site for it on Starlight.
Documentation like that can be fast, have a good SEO structure, comfortable navigation and a simple development process. No heavy panel, no database and no random plugins. Just a proper knowledge base that helps users find an answer before they email support. Let’s talk about how a solution like that might look for you.