Docusaurus, the React-based static site generator maintained by Meta’s open-source team, has released version 3.9. The new update focuses on modernizing the runtime environment, improving search capabilities with Algolia DocSearch v4 AI, and expanding internationalization (i18n) flexibility, while maintaining backward compatibility for existing documentation projects.
Docusaurus 3.9 introduces key updates across three areas: AI-powered search, runtime modernization, and global site management. The standout addition is full support for DocSearch v4, which brings Algolia’s new Ask AI feature directly into documentation sites. This allows users to query content conversationally, using an embedded chat-style assistant trained on the site’s indexed pages. Projects can remain on DocSearch v3 or upgrade incrementally to v4 to unlock the AI assistant. To upgrade, developers can use the npm update @docsearch/react command.
The release raises the Node.js baseline requirement to v20.0.0, dropping support for Node 18. While this change may impact CI/CD pipelines or containerized builds, it is not considered a breaking change since Node 18 has reached end-of-life and is no longer supported. Some developers have argued that due to the release dropping Node v18 support, it should have been considered a breaking change.
Docusaurus 3.9 includes improvements to the configuration for i18n. Developers can now override the baseUrl and url properties per locale using the new i18n.localeConfigs[locale] field, enabling multi-domain or deeply localized deployment setups.
Further improvements to i18n include a new translate flag which is set to false by default, this improves build times for sites that do not use translations. A new key attribute has also been added to sidebar items, enabling developers to assign keys to sidebar items explicitly.
The release also includes some translation fixes for Brazilian Portuguese and Ukrainian.
Additional improvements include Mermaid ELK layout support for richer diagram rendering and internal build optimizations through the Rspack 1.5 upgrade.
The migration process from 3.8 to 3.9 is designed to be minimal. The maintainers recommend verifying the Node.js version and reviewing search configuration if upgrading to DocSearch v4. Teams integrating Ask AI must ensure their Algolia crawler is updated and the appropriate credentials are added to the themeConfig.algolia section. Aside from this, there are no API-level breaking changes, and most sites can upgrade by simply updating their dependencies.
The release comes bundled with a number of other changes and fixes, with the full list of changes found here.
Docusaurus is an open-source framework for building modern documentation and content-driven websites using React. Originally developed and maintained by Meta and Facebook, it powers many large-scale open-source and enterprise documentation sites. You can find out more about the contents of the release on the website or on the Github discussion thread for the release.
