SpamBlocker Is an Open-Source Android App for Blocking Spam SMS and Calls

SpamBlocker is an open-source Android app for Android 10 and later, and it can be downloaded from GitHub or installed through F-Droid, while the latest releases are also available on the project page.

For calls, SpamBlocker acts as a caller ID app and does not replace the default phone or SMS apps. That means it checks incoming calls and filters unwanted ones without forcing users to change their usual setup.

SMS handling is split into two modes: Standalone Mode and Screening provider mode. In Standalone Mode, the app takes over SMS notifications, so notifications from the SMS app need to be turned off to avoid duplicates. In Screening provider mode, the SMS app checks messages in real time, and SpamBlocker replies with only "block" or "allow".

The project says Screening provider mode is the more flexible option because it can work without SMS permission and has better support for RCS and MMS. The catch is that one of the modes depends on whether the SMS app itself supports the SMS protocol, so the final choice is tied not just to convenience but also to compatibility.

SpamBlocker can also block SMS bombs, phishing, mass mailings, and continuous OTP floods. To do that, it checks contacts, contact groups, repeated calls, dialed and answered numbers, emergency calls, STIR/SHAKEN (caller-ID authentication), spam databases, geolocation, carrier name, CNAP, instant queries, and regex rules.

The project says offline features collect no data. For online features, the API endpoints can see the user's IP address, TLS and TCP fingerprints, and the reported number — and nothing more.

Would you trust a spam blocker whose best mode depends on your SMS app's protocol support?