Docusaurus, a React-based static site generator maintained by Meta's open-source team, has released version 3.9. This update focuses on modernizing the runtime environment, enhancing search capabilities, and expanding internationalization (i18n) flexibility through Algolia DocSearch v4 AI integration—all while maintaining backward compatibility with existing documentation projects.
Docusaurus 3.9 introduces key improvements in three areas: AI-powered search, runtime modernization, and global site management. The standout addition is full support for DocSearch v4, which integrates Algolia’s new “Ask AI” feature directly into documentation sites. This enables users to query content via an embedded chat assistant trained on the site’s indexed pages. Projects can continue using DocSearch v3 or gradually upgrade to v4 to unlock the AI assistant. Developers can upgrade by running npm update @docsearch/react.
This release raises the minimum Node.js requirement to v20.0.0, dropping support for Node 18. While this change may affect CI/CD pipelines or containerized builds, it is not classified as a breaking change since Node 18 has reached end-of-life and is no longer supported—though some developers argue that deprecating Node 18 warrants a major version bump.
Docusaurus 3.9 also enhances i18n configuration. Developers can now use the new i18n.localeConfigs[locale] field to override baseUrl and url properties per locale, enabling multi-domain or deeply localized deployment setups.
Additional i18n improvements include a new translate flag, defaulting to false, which accelerates builds for sites not using translations. A new key property has also been added to sidebar items, allowing developers to explicitly assign unique identifiers.
The release also includes translation fixes for Brazilian Portuguese and Ukrainian.
Other enhancements feature Mermaid ELK layout support for richer diagram rendering and internal build optimizations via the Rspack 1.5 upgrade.
Migrating from v3.8 to v3.9 is designed to be straightforward. Maintainers recommend verifying the Node.js version and reviewing search configuration when upgrading to DocSearch v4. Teams integrating Ask AI must ensure their Algolia crawler is updated and that proper credentials are added to the themeConfig.algolia section. Beyond these steps, there are no API-level breaking changes, and most sites can upgrade simply by updating dependencies.
This release bundles numerous additional changes and fixes. The full changelog is available here.
Docusaurus is an open-source framework for building modern, content-driven websites with React. Originally developed and maintained by Meta and Facebook, it powers documentation sites for many large open-source and enterprise projects. More details about this release can be found on the official website or in the GitHub release discussion thread.
