secure messaging app · Signal Foundation

Signal

Free, open-source messenger from a nonprofit, with end-to-end encryption on every chat and apps for five systems.

67/100

#5 of 12 secure messaging apps
Facts checked 8 Oct 2026

In short

The app is free for everyone; development is supported by grants and donations¹.
Encryption is not an optional mode: Signal says privacy is simply how the app works¹.
Apps exist for Windows, macOS, Linux, iOS and Android; desktop apps need Signal installed on a phone first².
Signal still needs a phone number to sign up, though usernames let contacts reach you without seeing it⁸.
Android, iOS and Desktop code is public under AGPL-3.0 on GitHub⁶.

Signal suits people who want strong default privacy at no cost, with public code and post-quantum key exchange^1,3,6. Secure Backups are end-to-end encrypted and optional⁵. The catch: you must register with a phone number, and no web app is listed^2,8.

Best for: People who want private chats by default and open-source apps, and accept sharing a phone number.

Where the points come from

Encryption20 of 20

Source and audits8 of 26

Sign-up and identity4 of 16

Chats and calls13 of 14

Systems14 of 16

Price8 of 8

Encryption 20 of 20 points

Rule	What is published	Points
End-to-end encrypted by default	YesSignal says privacy is not an optional mode; all conversations use end-to-end encryption, and group calls are described the same way^1,9.	12 / 12
Post-quantum key exchange	YesPQXDH, hybrid X25519 plus Kyber, is in use for chats started on current apps (2023). A post-quantum ratchet is rolling out^3,4.	4 / 4
Encrypted backups	YesSecure Backups are opt-in and end-to-end encrypted; a 64-character recovery key made on your device unlocks them⁵.	4 / 4

Source and audits 8 of 26 points

Rule	What is published	Points
Open-source apps	YesAndroid, iOS and Desktop repositories are public under AGPL-3.0⁶.	8 / 8
Independent audit since 2022	Not publishedNeither post links an audit report from a named outside firm; the ratchet post names research and verification partners^3,4.	0 / 10
Public bug bounty	NoHelp centre: Signal does not have a bounty program but investigates reported flaws^15,11.	0 / 4
Transparency report	Not publishedThe Government Requests page lists individual legal demands, latest 6 March 2026. It does not call itself a report or state a period⁷.	0 / 4

Sign-up and identity 4 of 16 points

Rule	What is published	Points
No phone number needed	NoSignal says you still need a phone number to sign up⁸.	0 / 12
Contacts by username	YesShare a username, link or QR code to connect without handing out your phone number⁸.	4 / 4

Chats and calls 13 of 14 points

Rule	What is published	Points
Disappearing messages	YesTimers apply per one-to-one chat or group, and the help centre allows custom times up to 4 weeks^16,12.	5 / 5
Largest group chat	1000Help centre: group chats have a size limit of 1000¹³.	3 / 4
Encrypted voice and video calls	YesGroup calls are end-to-end encrypted, 'like everything else on Signal'; the home page lists voice and video calls and says privacy is not optional^1,9.	5 / 5

Systems 14 of 16 points

Rule	What is published	Points
Apps	Windows, macOS, Linux, iOS, AndroidThe download page lists all five; no web app and no beta labels².	10 / 12
Windows works without the phone	YesHelp centre describes linked devices that keep connecting to Signal while the phone has not connected for a while¹⁴; Desktop links to a phone first^2,10.	4 / 4

Price 8 of 8 points

Rule	What is published	Points
Cost for one person	$0The app is free for everyone; optional Secure Backups are an extra and are ignored^1,5.	8 / 8

The rule behind each line: how we score secure messaging apps.

Plans and prices

As the vendor lists them, before tax. Prices are in US dollars unless the plan shows euros; the points use US dollars, with euros converted at the ECB rate.

Plan	Price as listed	Per month	Notes
Signal1 person	Free¹	$0	Messaging and calls are free
Secure Backups paid tier1 person	$1.99/month⁵	$1.99	Optional; free tier keeps 100 MiB of messages and 45 days of media

Secure Backups are an optional extra and the price may change, as the launch post states⁵.

Strengths

Free for everyone; development is supported by grants and donations¹.
Uses PQXDH, a hybrid post-quantum key agreement, for chats started on current versions³.
Opt-in Secure Backups are end-to-end encrypted with a 64-character recovery key made on your device⁵.
Contacts can add you by username, link or QR code without seeing your phone number⁸.
Group chats hold up to 1,000 members¹³.

Limits

A phone number is still required to sign up⁸.
No web app is listed; the desktop app needs Signal on a phone first².
Signal's posts name research and verification partners but link no audit report⁴.
Secure Backups beyond the free tier cost $1.99 a month⁵.
Signal has no bug bounty program¹⁵.

What Signal Foundation says

Vendor claims. We show them, but they earn no points.

Signal says its post-quantum ratchet is being rolled out slowly and will be enforced for all sessions once all clients support it⁴.

Other secure messaging apps

1
SimpleX ChatPeople who want a messenger that holds no account identifier or phone number
86/100
$0cost for one person
2
ThreemaPeople who want a messenger with no phone number and no subscription
79/100
$6/yrcost for one person
3
WirePeople who want default encryption and open-source apps without handing over a phone number
78/100
$0cost for one person
4
ElementPeople who want open-source apps on every platform and no phone number
69/100
$0cost for one person

All 12 secure messaging apps

Sources

Signal: Speak Freely, Signal. Accessed 8 Oct 2026.
Download Signal, Signal. Accessed 8 Oct 2026.
Quantum Resistance and the Signal Protocol, Signal. Accessed 8 Oct 2026.
Signal Protocol and Post-Quantum Ratchets, Signal. Accessed 8 Oct 2026.
Introducing Signal Secure Backups, Signal. Accessed 8 Oct 2026.
signalapp, GitHub. Accessed 8 Oct 2026.
Government Requests, Signal. Accessed 8 Oct 2026.
Keep your phone number private with Signal usernames, Signal. Accessed 8 Oct 2026.
Adding Encrypted Group Calls to Signal, Signal. Accessed 8 Oct 2026.
signalapp/Signal-Desktop, GitHub. Accessed 8 Oct 2026.
Security overview, signalapp/Signal-Android, GitHub. Accessed 8 Oct 2026.
Disappearing messages for Signal, Signal. Accessed 8 Oct 2026.
Group chats, Signal. Accessed 8 Oct 2026.
Open Signal on your phone to keep your account active, Signal. Accessed 8 Oct 2026.
How can I report a security vulnerability?, Signal. Accessed 8 Oct 2026.
Set and manage disappearing messages, Signal. Accessed 8 Oct 2026.

Website: signal.org · Markdown version · We are not affiliated with Signal Foundation.