← Communication & Background
Background Fetch
Probing…Background Fetch is a web platform capability in the Communication & Background category. Large downloads/uploads that outlive the page. Supported in Chromium 74+; not available in Firefox and Safari. Requires a secure context (HTTPS or localhost).
Secure context
Try it
Loading demo…
Code
const reg = await navigator.serviceWorker.ready
const bgFetch = await reg.backgroundFetch.fetch(
'demo-download',
['/pwa-192x192.png'],
{ title: 'Demo download' },
)
bgFetch.addEventListener('progress', () => {
console.log(bgFetch.downloaded, '/', bgFetch.downloadTotal)
})Browser support
Chromium
74
Firefox
No
Safari
No
Frequently asked questions
Which browsers support Background Fetch?
Supported in Chromium 74+; not available in Firefox and Safari.
Does Background Fetch require HTTPS?
Yes. Background Fetch needs a secure context, so it only works over HTTPS (or on localhost during development).
What is Background Fetch used for?
Large downloads/uploads that outlive the page.
Can I try Background Fetch in my browser?
Yes. shwcs.net runs a live Background Fetch demo that probes your current browser and lets you try the API. Everything runs locally — nothing is sent anywhere.