Defndr
Private. Offline. Zero-Compromise Security.
Instant Blocking
Filter unwanted SMS junk in real-time before it hits your inbox.
On-Device Filter
Local analysis only. Your messages never touch a server.
Custom Rules
Manage your own keyword allowlists and blocklists.
Ad-Free
Pure, uninterrupted experience with absolutely no tracking.
Why 100% Offline Matters
Unlike cloud-based spam filters that upload your messages to remote servers for analysis, Defndr processes everything locally on your device. This means your SMS messages—including sensitive information like verification codes, banking alerts, and personal conversations—never leave your iPhone.
Cloud-based filtering services create permanent records of your messages, building detailed profiles of who you communicate with, when, and what keywords appear in your texts. Even if they claim data is "anonymized," the metadata alone can be incredibly revealing. With Defndr, there's no server, no database, and no one analyzing your messages but your own device.
The filtering happens in real-time using pattern matching and custom rules you control. Fast, private, and completely transparent. Your messages are yours alone.
Cloud-Based vs. On-Device Filtering
Cloud-Based Filters
- Messages uploaded to servers
- Creates permanent records
- Metadata collection
- Third-party access possible
- Requires internet connection
Defndr (On-Device)
- 100% local processing
- Zero data storage
- No metadata collection
- No third-party access
- Works completely offline
Does Defndr scan my messages online?
No. Defndr performs all filtering locally on your iPhone. Your messages never leave your device, and there are no cloud servers involved. Everything happens offline.
Does it collect any data?
No. Defndr doesn't collect, store, or transmit any data. No analytics, no telemetry, no tracking. We don't even have servers to send data to.
Is it really open source?
Yes. Defndr's core filtering logic is open source and available on GitHub. You can audit the code yourself to verify there's no tracking or hidden behavior.
How does it block spam without a database?
Defndr uses pattern matching and keyword-based filtering that runs entirely on your device. You can customize rules to match your needs. No external spam database means no data leaves your iPhone.
Does it work offline?
Yes, completely. Since all processing happens on-device, Defndr works perfectly in airplane mode or anywhere without an internet connection.
Are there ads?
No ads. Ever. Defndr is free to download with limited features. Unlock full access with annual subscription or lifetime purchase.