Most people use WhatsApp because their contacts are on it, or iMessage because they have an iPhone. Neither of those is a particularly strong reason if privacy matters to you. Signal is the messaging app that security researchers, journalists, and privacy advocates consistently recommend above every other option, and it does everything WhatsApp and iMessage can do, including text, voice calls, video calls, and file sharing. It is free, open-source, and available on Windows, Mac, Android, and iOS. This guide explains what Signal is, how it compares to the alternatives, and how to get started on Windows.
What Is Signal?
Signal is a free, open-source encrypted messaging app developed by the nonprofit Signal Foundation. It was created by cryptographer Moxie Marlinspike in 2013 and has since grown to over 70 million active users worldwide. It is available on Android, iOS, Windows, macOS, and Linux.
Every message, voice call, video call, and file sent through Signal is end-to-end encrypted by default using the Signal Protocol, which is widely regarded as the strongest encryption standard in consumer messaging. The Signal Protocol is so well regarded that WhatsApp and Google Messages both adopted it for their own encryption. The difference is that Signal's entire codebase is publicly available and has been independently audited by security researchers, while WhatsApp's implementation is closed source and cannot be verified.
Signal is run by a nonprofit organization with no advertising revenue and no investors to satisfy. It collects the absolute minimum data needed to operate: your phone number, the date your account was created, and the date you last connected. Nothing else.
How Signal Works
Signal functions like any other modern messaging app. You register with your phone number, add contacts who also use Signal, and start messaging. On Windows, Signal runs as a desktop app linked to your phone account. You can send and receive messages, make calls, and share files from your PC while your phone account stays in sync.
Messages are stored on your device, not on Signal's servers. Once delivered, Signal does not retain your messages. This means there is no inbox sitting on a company server that could be hacked, subpoenaed, or sold.
Signal vs WhatsApp vs iMessage: Feature Comparison
| Feature | Signal | iMessage | |
|---|---|---|---|
| Price | Free | Free | Free (Apple only) |
| Platform | Windows, Mac, Linux, Android, iOS | Windows, Mac, Android, iOS | Mac, iOS only |
| End-to-end encryption | All messages by default | All messages by default | Apple devices only |
| Encryption protocol | Open-source Signal Protocol | Signal Protocol (closed implementation) | Apple proprietary (closed) |
| Open-source | Yes, fully audited | No | No |
| Metadata collected | Phone number and last seen date only | Phone number, contacts, IP address, usage data, device info | Phone number, limited usage data |
| Owned by | Signal Foundation (nonprofit) | Meta (Facebook) | Apple |
| Disappearing messages | Yes, configurable | Yes | Yes |
| Group chats | Yes, up to 1000 members | Yes, up to 1024 members | Yes |
| Voice and video calls | Yes | Yes | Yes |
| Works without smartphone | No, phone required for registration | No | No |
| Windows desktop app | Yes | Yes | No |
| Android support | Yes | Yes | No |
| Note editing | Yes | Yes | Yes |
| Screen security | Yes (blocks screenshots) | No | No |
Privacy Comparison: Where the Real Differences Are
The feature list above shows that all three apps are broadly capable. The meaningful differences emerge when you look at privacy and data handling.
| Privacy Factor | Signal | iMessage | |
|---|---|---|---|
| Data sold to advertisers | Never | Used within Meta ecosystem | Never |
| Metadata protection | Sealed Sender hides who messages whom | Metadata shared with Meta and third parties | Limited metadata retained |
| Cloud backup encryption | Encrypted locally, no default cloud backup | Backup to Google Drive or iCloud not always E2E encrypted | iCloud backup can be accessed by Apple |
| Government data requests | Can only provide phone number and last seen date | Can provide more account data and metadata | Apple can provide iCloud backup contents |
| Code auditable by security researchers | Yes, fully open-source | No | No |
| Ad targeting | None, nonprofit | Yes, contributes to Meta ad profile | None |
The core issue with WhatsApp is not its encryption, which is technically sound for message content. It is that WhatsApp is owned by Meta, collects significant metadata about your usage patterns, and shares data across the Meta ecosystem. Your messages may be private but who you talk to, how often, at what times, and from which location are all data points Meta has access to.
iMessage is well implemented for Apple users but has two significant limitations. It only works between Apple devices. Messages sent to Android users fall back to unencrypted SMS. And if you use iCloud Backup, your iMessage history may be included in that backup, which Apple can access under legal compulsion.
Signal's approach is structurally different. Even if compelled by a court order, Signal can only hand over your phone number and the date you created your account and last used the app. It has demonstrated this multiple times in court cases. There is simply nothing else to provide.
Key Signal Features Worth Knowing
Disappearing Messages lets you set a timer on any conversation so that messages automatically delete after a chosen period, from 30 seconds to four weeks. This happens on both devices automatically.
Note to Self is a private note-taking feature where you can send messages, files, and links to yourself, synced across all your Signal devices. It works as a private clipboard across your phone and PC.
Screen Security prevents other apps on your device from taking screenshots of your Signal conversations. On Windows, Signal blurs its content in the taskbar preview so your conversations are not visible when switching between apps.
Sealed Sender is a behind-the-scenes feature that hides metadata about who is sending a message to whom, even from Signal's own servers. This goes significantly beyond what WhatsApp or iMessage offer.
Safety Numbers lets you verify with another person that your encrypted connection has not been tampered with. Both users compare a unique safety number and if they match, the connection is confirmed secure. This prevents man-in-the-middle attacks.
Signal Phone Number Privacy lets you share a username instead of your phone number with new contacts, so people can reach you on Signal without knowing your actual number. This was added in 2024 and significantly strengthens privacy for users who do not want to share their phone number publicly.
How to Install Signal on Windows
Go to signal.org and click Download for Windows. Run the installer. Signal opens and prompts you to link to your phone.
On your phone, open Signal, go to Settings, then Linked Devices, and tap the plus icon to add a device. Scan the QR code shown on your Windows screen. Signal will sync your contacts and conversation history to the desktop app. From that point, your Windows Signal app stays in sync with your phone automatically.
Note that your phone must have Signal installed and registered before you can use the Windows app. Signal requires a phone number to register, though you can use a username instead of your number when sharing your contact details with others after registration.
Who Should Use Signal
Signal is the right choice for anyone who wants private communication without trusting a large corporation with their data. This includes people who want their conversations to stay genuinely private, anyone communicating sensitive personal or professional information, journalists and researchers who work with confidential sources, and anyone who simply believes their private conversations should be private by default.
Signal is not a fringe tool for extreme privacy advocates. It is used by millions of ordinary people worldwide who have made a considered choice about which company they want handling their communications.
The main practical barrier is adoption. Signal works best when the people you communicate with also use it. The most effective approach is to install it yourself, then invite a few key contacts. Many people find that once they try it, the experience is so similar to WhatsApp that switching is not the significant change they expected.
Final Thoughts
Signal, WhatsApp, and iMessage all send messages and make calls. The difference is in what happens to the data surrounding those communications, who owns the platform, how it is funded, and what could theoretically be accessed by governments or companies. Signal wins clearly on every one of those measures. It is free, it works on every platform including Windows, it is run by a nonprofit with no advertising motive, and its security has been verified by independent researchers worldwide. If you have been looking for a reason to try it, this is it.
Frequently Asked Questions
Is Signal really more private than WhatsApp?
Yes. Both apps use end-to-end encryption for message content, but Signal collects far less metadata than WhatsApp. WhatsApp is owned by Meta and shares usage data across the Meta ecosystem. Signal is run by a nonprofit and can provide nothing more than your phone number and last seen date even under a court order.
Does Signal work on Windows?
Yes. Signal has a dedicated Windows desktop app available from signal.org. It links to your phone account and syncs messages and contacts automatically. Your phone must have Signal registered before you can use the Windows app.
Can I use Signal without giving out my phone number?
You need a phone number to register a Signal account, but since 2024, Signal allows you to create a username that you can share with others instead of your actual phone number. People can find and contact you on Signal using your username without ever knowing your number.
Why is iMessage not available on Windows or Android?
iMessage is an Apple proprietary service built exclusively into Apple devices. It does not support Android or Windows. Messages sent from an iPhone to a non-iPhone fall back to standard unencrypted SMS. Signal is cross-platform and works across all major operating systems.
Is Signal free to use?
Yes. Signal is completely free with no ads, no subscription, and no paid features. It is funded by donations and grants to the Signal Foundation, a nonprofit organization. There is no premium tier.
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