difference between getSignedUrl() and getDownloadUrl()

Question

what is the difference between get getSignedUrl() method I get on the Node.js vs getDownloadURL() on the SDKs? (I use flutter)

with getSignedUrl() I use in the cloud function, the returned url does not change when the image changes (with the same file name)

but getDownloadURL() on the client side code returns correct and varying urls when the image changes.

Answer 1

They're mostly functionally equivalent, as they both provide direct download access to the underlying object.

Signed URLs have an explicit expiration that that you provide.

Signed URLs can use some forms of authentication, which you can read about in the documentation.

Signed URLs can also be used for resumable uploads.

Download URLs obtained from the web and mobile client libraries can do none of the above. But they have an access token that you can revoke in the Firebase console, which makes any URLs using that token to stop working (the token string is in the URL itself).