Block and allow lists
Filter by sender, full or partial number, keyword, country prefix, and wildcard patterns.
Android SMS filtering, fully on device
SMS Shield
A privacy-first Android SMS app for people who want direct control over their inbox: local rule-based filtering, block and allow lists, archive tools, OTP support, and no data connectivity.
Open source
GPL-3.0-only
No Internet permission
Rule-based filtering
Installation notes for sideloaded APKs
The recommended install path is IzzyOnDroid. Manual APK installation from GitHub is also available for users who prefer direct downloads.
When installing the release APK manually, some Android versions may show warning messages. You may need to pause Google Play Protect temporarily.
Pause Play Protect temporarily
- Open the Google Play Store app.
- Tap the profile icon in the top right corner.
- Open Play Protect.
- Tap the settings icon in the top right corner.
- Deactivate "Scan apps with Play Protect".
- When asked to confirm, select "Pause".
After installation, you can reactivate Play Protect. Subsequent updates usually install without disabling Play Protect, though Android may ask you to approve the installation with your fingerprint or system PIN. If shown, open "More details" and choose "Install anyway".
Set SMS Shield as the default SMS app
Android 13 and newer may require one additional approval step for sideloaded apps that request SMS-related access.
- Open Settings, then Apps, then App management.
- Find SMS Shield.
- Tap the three-dot menu in the top right corner and activate "Allow restricted settings".
- Open Settings, then Default apps, then SMS app.
- Select SMS Shield.
Built for a quieter SMS inbox.
SMS Shield keeps the core messaging workflow familiar while adding practical controls for clutter, carrier spam, short-code messages, bank alerts, travel texts, and recurring promotions.
Unicode-ready matching
Rules support non-ASCII text, including messages with Chinese characters and mixed-language content.
Inbox, archive, blocked
Keep normal messages visible, move clutter to archive, and inspect blocked messages separately.
Conversation view
Messages can be grouped as chats, with configurable inactivity splitting and sender-aware behavior.
OTP support
One-time codes can be copied from notifications while keeping message handling local.
Dual-SIM aware
Send with a selected SIM, choose default sending behavior, and preserve received-on-SIM details.
Transparent rules, not mystery scoring.
SMS Shield does not try to guess what spam is with cloud models or opaque reputation services. You define the rules, the app applies them locally, and blocked messages can show which rule matched.
Filtering tools
- ✓Block or allow keywords, phrases, sender IDs, and phone numbers.
- ✓Use wildcard patterns for flexible matching.
- ✓Block whole country prefixes with configurable calling-code rules.
- ✓Prevent contradictory rules with conflict prompts.
- ✓Move matching old messages when adding new rules.
- ✓Export and import settings, rules, and message folders as JSON.
Privacy posture
- ✓No web services or data connectivity.
- ✓No advertising SDKs, analytics SDKs, Firebase, Google Play Services, or AI services.
- ✓No cloud spam detection and no server-side message processing.
- ✓Pure rule-based on-device handling.
Your messages stay on your phone.
SMS Shield is designed for users who want SMS management without online classification, account systems, tracking SDKs, or third-party messaging infrastructure.
Source code is available on GitHub under GPL-3.0-only.