Can Android block an app on mobile data but not Wi-Fi?

Not on its own. Android's per-app switch turns off background data, which is about when an app may use the network, not which network. There is no built-in per-app, per-network control.

What does turning off background data actually do?

It stops the app using mobile data while you are not in it. The app still uses mobile data freely when you open it, and it is unaffected on Wi-Fi.

Why does a per-network blocker need VPN permission?

Without root, VpnService is the only API that lets an app decide which other apps may reach the network. A blocker can use it in package-list mode, naming the apps allowed through and forwarding no packets at all, so nothing is routed, read or captured.

Block an app on mobile data but keep it on Wi-Fi

The request is simple enough. One app — a store, a game, a social app — is expensive, and you would like it to carry on working normally at home and stop touching your bundle when you leave. Allowed on Wi-Fi. Blocked on mobile.

Android has no setting for that. It is worth being clear about it up front, because a lot of pages imply otherwise and send people hunting through Settings for a switch that was never there.

What the built-in settings really do

There are three controls that look like they might be the answer. None of them is.

1. Background data (per app)

Settings → Network & internet → App data usage → tap the app → Background data.

This is about when, not which network. It stops the app spending while you are not in it. Open the app and it uses mobile data as freely as before. On Wi-Fi it changes nothing.

Genuinely useful — it is the single most effective built-in control, and for a lot of apps it solves the real problem. It just isn't a per-network switch. More on what it does and the one thing not to restrict.

2. Android's own Data Saver

Mobile-data-only, which sounds promising, but it applies to every app at once and only to background traffic. You then add exceptions one by one. It is an emergency brake for the end of a bundle, not a per-app rule.

3. Metered Wi-Fi

You can mark a Wi-Fi network as metered so apps treat it like mobile data. That is the opposite direction — it restricts Wi-Fi, it cannot free it.

Why the gap exists. Android's model is "is this connection expensive?", not "which app may use which connection". Apps are expected to check whether the network is metered and behave. Many do not, and nothing makes them.

What a real per-network switch requires

Deciding which apps may reach the network is a privileged thing to do. Without root there is exactly one API for it: VpnService. That is why every no-root firewall or blocker on Android asks for VPN permission, and why the key icon appears in your status bar.

It is worth understanding, because the permission sounds far more invasive than what it is being used for here.

A blocker does not have to route your traffic anywhere.

VpnService can be used in package-list mode: the app names which packages are allowed through and never reads the tunnel. No packets are forwarded, inspected, captured or sent to a server. The connection exists only so the system has something to point the blocked apps at.

That is a real distinction, not a reassuring phrase. A traffic-compressing or privacy VPN genuinely does route everything you do through someone else's servers. A package-list blocker cannot — there is nowhere for it to go.

The way to tell the difference is the INTERNET permission. An app without it cannot open a network connection at all, whatever its code says.

The trade-off worth knowing before you install anything

Android allows one active VPN at a time. Anything using VpnService to block apps therefore occupies that slot, and cannot run alongside an actual VPN. If you need an always-on VPN, no no-root blocker will work for you, and that is a hard limit rather than a shortcoming of any particular app.

Several open-source apps do this, with different aims — some are full firewalls with per-connection rules, some add DNS filtering. If you want exhaustive control, look at those.

What we make

Data Saver takes the narrow version of the problem: see what each app spent, and block the expensive ones per network, from the same row.

App list ranked by mobile data, each row showing foreground and background usage with its own restriction switch — Usage and the switch on one row, with mobile and Wi-Fi controlled separately.

It has no INTERNET permission. The permission is absent from the manifest, so Android will not let it open a socket — it could not send your traffic anywhere if it tried. It uses VpnService in package-list mode with no packet forwarding, exactly as described above. No accounts, no analytics, no servers, no ads, and the source is public, so this is checkable rather than a promise.

Google Play Source code

Free, no ads, works offline. Requires Android 7.0 or later.

Which app is using your mobile data — find the culprit before you block anything
Stopping background data — the three built-in ways, and the switch that silences every notification
Why your bundle runs out early — the arithmetic, and which half of your usage is worth cutting
Why the Play Store eats your mobile data — usually the single biggest offender, and a one-line fix

Blocked on mobile, fine on Wi-Fi