The <install> Element

The <install> element is a declarative HTML element that allows web developers to offer installation of web applications directly from a page. It renders a user-agent-controlled button whose text and iconography are determined by the browser, providing a strong signal of user intent and protection against spoofing. The element is part of the Permission Element family, sharing the same security model, styling restrictions, and validation infrastructure.

The <install> element is one of two entry points to web app installation initiated by a website. The other is the Web Install API - navigator.install() - which provides a promise-based JavaScript entry point. Both share a single backend implementation — manifest fetch, validation, consent UI, and error taxonomy.

Authors

• Lia Hiscock (Microsoft)
• Mike West (Google)

Participate

• Issue tracker
• Chromestatus

Explainers

There are currently two explainers for the <install> element that reflect two different methods of specifying which web app to install. One accepts an installurl, and the other accepts a manifest URL.

Install-URL design (installurl / manifestid)

explainer-install-url.md

Here for Origin Trials? Use this explainer.

• Attributes: installurl (a page URL) and manifestid (the app's computed manifest id).
• How it works: On activation, the element loads the page at installurl in the background, discovers its <link rel="manifest">, fetches and validates the manifest, then presents the installation dialog.
• This design will reach end of life at its Origin Trial conclusion.

Manifest-URL design (manifest / id)

explainer-manifest-url.md

• Attributes: manifest (a manifest URL) and id (the app's computed manifest id).
• How it works: On activation, the element fetches the manifest directly from the supplied URL, skipping the intermediate page load.
• This design eliminates the document-fetch step, reducing latency and removing the cross-origin HTML parse surface. It is expected to replace the install-URL design.

Stakeholder Feedback

• W3C TAG Review: PENDING
• Browser Standards Positions:
  • Chromium: Supportive/Implementing
  • Mozilla: mozilla/standards-positions#1179
  • WebKit: WebKit/standards-positions#463

References & Acknowledgements

This proposal builds on the Permission Element (PEPC) infrastructure and the Web Install API.

Many thanks for valuable feedback and advice from:

• Daniel Murphy
• Rob Paveza
• Lu Huang
• Alex Russell
• Arthur Sonzogni