What Is Signal?
Signal is a free, open-source messaging and calling app developed by the nonprofit Signal Foundation. It was originally built with privacy as its core design principle, and over time has grown from a niche tool used by journalists and activists into a mainstream app with millions of users worldwide.
Unlike commercial apps, Signal has no advertising business model and does not sell or use your data. The app is funded by donations and grants.
Key Features
- Voice and video calls: Free, high-quality calls to other Signal users over Wi-Fi or mobile data
- End-to-end encryption: All calls, messages, and file transfers are E2EE using the Signal Protocol — the same protocol adopted by WhatsApp and others
- Disappearing messages: Set messages to auto-delete after a chosen time period
- Screen security: Prevents screenshots within the app on mobile
- Note to self: Encrypted personal notes and file storage
- Group calls: Supports group voice and video calls
- Desktop app: Available for Windows, macOS, and Linux
- No ads, no trackers, no data selling
Call Quality: How Does It Sound?
Signal's voice call quality is generally very good on a stable internet connection. It uses modern audio codecs and adapts well to varying connection speeds. On a strong Wi-Fi connection, calls are clear and natural. On slower mobile data connections, you may notice some compression, but calls remain usable in most cases.
Video calls are similarly solid for one-on-one conversations, though large group video calls can strain lower-end devices.
Ease of Use
Signal's interface is clean and intuitive — very similar in layout to standard messaging apps. If you've used WhatsApp or iMessage, you'll feel at home immediately. The settings menu offers granular privacy controls for users who want to customize their experience, without overwhelming casual users.
One friction point: Signal requires a phone number to register. While this is necessary for its identity system, users who prefer fully anonymous communication may prefer alternatives like Briar or Session.
Signal vs. WhatsApp: The Most Common Comparison
| Feature | Signal | |
|---|---|---|
| End-to-end encryption | ✅ Always, all features | ✅ Calls & messages (not backups by default) |
| Metadata collection | Minimal | Collects metadata for Meta |
| Open source | ✅ Fully | ❌ Proprietary |
| Business model | Nonprofit / donations | Meta advertising ecosystem |
| User base | Smaller but growing | Very large (global dominance) |
| Disappearing messages | ✅ Yes | ✅ Yes |
| Cloud backup encryption | ✅ E2EE by default | ⚠️ Optional |
Who Should Use Signal?
Signal is an excellent choice for:
- Anyone who values privacy and doesn't want their communication data used for advertising
- Journalists, activists, lawyers, or anyone handling sensitive information
- Users in countries where communication may be monitored
- People looking for a simple, trustworthy replacement for SMS and standard calls
It may not be the best primary calling app for users whose entire social circle is on WhatsApp, simply due to the network effect — the app only works when the other person also has Signal installed.
Verdict
Signal delivers on its privacy promises better than virtually any other mainstream calling app. It's free, well-designed, and backed by a credible nonprofit organization. The main barrier is adoption: you need the people you call to also use it. For anyone who takes digital privacy seriously — or who handles sensitive communications professionally — Signal is the clear recommendation.
Rating: Excellent for privacy-focused users. Best in class for E2EE communication.