🟢 Trust Rating: High

Signal is widely recommended by security experts, uses proven encryption, and has a strong track record of protecting user privacy.

What is Signal?

Signal is an end-to-end encrypted messaging app developed by the non-profit Signal Foundation. Created by cryptographer Moxie Marlinspike and WhatsApp co-founder Brian Acton, it's become the standard for secure communications among journalists, activists, and privacy-conscious users worldwide.

Key Features

Core Security

End-to-end encryption - All messages, calls, and files
Signal Protocol - The gold standard, used by WhatsApp
Disappearing messages - Auto-delete after set time
Screen security - Blocks screenshots in app
No ads or tracking - Non-profit model

Communication Features

Text messaging
Voice calls
Video calls
Group chats (up to 1000 members)
File sharing (200MB limit)
Voice notes
Reactions and stickers
Story feature

Privacy Architecture

What Signal Knows

✅ Phone number (unless you register with Signal Login)^[2]

✅ Last connection date (not time)^[4]

What Signal DOESN'T Know

❌ Your contacts

❌ Who you message

❌ Message content

❌ Group memberships

❌ Profile information

❌ Location data

Setup Guide

Getting Started

Download Signal from official sources only
Register with phone number (Signal Login is the alternative on Android)^[2]
Set up PIN for account recovery
Verify safety numbers with contacts
Enable disappearing messages by default

Recommended Settings

Enable registration lock - Prevents SIM swap attacks
Turn on screen lock - Requires biometric/PIN
Disable link previews - Prevents metadata leaks
Hide keyboard personalization - Stops learning
Enable relay calls - Hides IP address

Security Features Explained

Sealed Sender

Hides who's messaging whom from Signal servers. Even Signal can't see the sender's identity.

Safety Numbers

Cryptographic fingerprints that verify you're talking to the right person. Always verify for sensitive conversations.

Automatic Key Verification

Added in August 2026. Key transparency lets Signal confirm a contact's encryption keys without you comparing safety numbers by hand. Cloudflare and Trail of Bits serve as the trusted third-party auditors, and you can switch the feature off under Privacy, Advanced. It needs your contact's phone number, so it will not work with someone you know only by username.^[3]

Disappearing Messages

Messages auto-delete after:

30 seconds to 4 weeks
Custom timer per conversation
Applies to all message types

Screen Security

Blocks screenshots within app (Android)
Blurs app in recent apps
Face blur for video calls
Incognito keyboard mode

Limitations & Concerns

Phone Number Requirement

The biggest weakness: Most accounts are tied to a phone number, which can be subpoenaed or SIM-swapped. Android users can now skip the number entirely with Signal Login, an optional registration method that costs a one-time payment and issues an Account ID and recovery key instead.^[2] Mitigation strategies:

Use burner phone for registration
Enable registration lock
Use Signal PIN
Register with Signal Login instead of a number if you can spare the payment
Consider Session or Briar for anonymous messaging

Metadata Collection

Signal keeps two pieces of account data that it can produce when it is forced to answer a legal request:

Account creation date and time
Date of last connection (the date, not the time)

Everything else is either end-to-end encrypted or never collected in the first place.^[4]^[5]

US Jurisdiction

Based in United States
Subject to US laws
Can be compelled to provide data (though they have little)

Signal vs. Alternatives

Signal vs. WhatsApp

Signal: Non-profit, minimal data, open source
WhatsApp: Meta-owned, metadata collection, closed source

Signal vs. Telegram

Signal: Default E2EE, proven crypto, non-profit
Telegram: No default E2EE, questionable crypto, for-profit

Signal vs. Element/Matrix

Signal: Easier setup, phone number required
Element: Decentralized, anonymous possible, complex

Signal vs. Session

Signal: Requires phone number, more features
Session: No phone number, based on Signal protocol

Real-World Usage

Perfect For:

Journalists protecting sources
Activists organizing safely
Lawyers with privileged communications
Whistleblowers sharing information
Anyone wanting private conversations

Not Ideal For:

Anonymous communication (most accounts still need a phone number)
Very large file transfers (200MB limit)
Users in countries where Signal is blocked
Those avoiding all US-based services

Articles Referencing Signal

Advanced Usage

Using Signal with Tor

Enable Orbot on Android
Set Signal to use Tor proxy
Enables censorship circumvention
Hides IP from Signal servers

Burner Phone Setup

Buy prepaid phone with cash
Activate away from home
Register Signal account
Never use with personal phone on
Keep powered off when not needed

Group Security

Verify all members' safety numbers
Use disappearing messages
Limit group size
Avoid sensitive group names
Regularly review members

Government Requests

What Signal Has Provided

In response to legal requests, Signal can only produce:

The date and time an account was created
The date an account last connected to Signal (the date, not the time)

Latest example: A grand jury subpoena from the United States District Court for the District of Columbia, issued October 5, 2026, sought account information for four phone numbers. Three of those accounts did not exist. For the one that did, Signal supplied the account creation date and time and the date of its last connection, and nothing else.^[4]

What Signal Does Not Have

Signal says it keeps no records of your contacts, your group memberships, who you have been communicating with, or your message content. It cannot hand over what it never collected.^[5]

Transparency

Signal publishes the transcripts of the government requests it is forced to answer, with redactions applied, and has done so for every request it has received since 2016.^[5]

Common Issues

Message Delivery

Requires internet connection
Both parties must have Signal
Notifications can be delayed
Battery optimization can interfere

Verification Problems

Phone number changes require re-registration
Safety numbers change with reinstalls
Group members need individual verification

Tips for Maximum Security

Operational Security

Verify safety numbers in person
Use disappearing messages always
Avoid SMS fallback - Signal phased out plaintext SMS support in its Android app because SMS is not encrypted^[8]
Regular safety number checks
Back up deliberately - Signal now offers on-device backups and opt-in Signal Secure Backups, both end-to-end encrypted. Know where your recovery key lives before you need it.^[6]^[7]

Physical Security

Enable app lock
Use complex PIN
Hide notifications content
Enable registration lock
Regular app updates

Development & Transparency

Open Source

Client code on GitHub
Server code on GitHub
Reproducible builds
Regular security audits
Active development

Funding Model

Non-profit Signal Foundation
Initial $50M from Brian Acton
Donations from users
No ads or data sales
Sustainable operations

Getting Signal

Official Downloads

Signal.org
Apple App Store
Google Play Store
Direct APK download
Desktop apps (Windows, Mac, Linux)

Verify Authenticity

Always verify downloads:

Check website certificate
Verify app signatures
Use official sources only
Check SHA256 hashes

Frequently Asked Questions

Is Signal really secure?

Yes. Signal uses the most advanced end-to-end encryption protocol available, has been audited multiple times, and is recommended by security experts worldwide.

Can government agencies read Signal messages?

No. Due to end-to-end encryption, not even Signal can read your messages. Government agencies would need physical access to your unlocked device.

Why does Signal need my phone number?

Phone numbers prevent spam and enable contact discovery. It's Signal's biggest privacy trade-off for usability.

Is Signal blocked in my country?

Signal is blocked in China, Iran, Egypt, UAE, and others. Use Signal's censorship circumvention (domain fronting) or Tor.

Can I use Signal anonymously?

Not by default. Most accounts are tied to a phone number, though Android users can register with Signal Login instead.^[2] For anonymous messaging, consider Session or Briar.

The Bottom Line

Signal remains the best option for secure messaging for most users. While the phone number requirement is a limitation, the security benefits far outweigh this for non-anonymous use cases.

Use Signal when:

You need proven, audited encryption
Communicating sensitive information
Ease of use matters
You trust US-based services

Consider alternatives when:

Anonymous communication is required
Avoiding US jurisdiction
Decentralization is priority
Phone number registration is dealbreaker

Ready for Secure Messaging?

Download Signal from official sources and start protecting your communications today.

Download Signal →