Signal vs SimpleX

Choose two to four messengers. Every property comes from the same traceable catalogue; unknowns remain explicit.

Property	Signal	SimpleX
Account identifier	SignalRegistration phone number; optional username. [1] [2]	SimpleXLocal profile; relationship-specific invitations. [1] [2]
Phone required by service	SignalYes, even when hidden from the contact. [1] [2]	SimpleXNot required. [1] [2]
E2EE	SignalMature E2EE for messages and calls; endpoint security remains crucial. [1] [2]	SimpleXDouble Ratchet E2EE; message padding is declared. [1] [2]
Metadata exposure	SignalService knows the number; some account dates were publicly disclosed. [1] [2]	SimpleXNo global account; relays, queues, timing and iOS push remain exposure surfaces. [1] [2]
IP exposure to peer	SignalCalls can be relayed; check the setting and actual network path. [1] [2]	SimpleXDefault TURN hides IP from the peer; P2P can reveal it. [1] [2]
Multi-device	SignalPrimary iPhone; official desktops linked through the phone. [1] [2]	SimpleXDocumented mobile–desktop pairing on the same local network; desktop beta. [1] [2]
Main strength	SignalMature content security, adoption and iPhone + PC usability. [1] [2]	SimpleXRelationship separation without a mandatory global identifier. [1] [2]
Main weakness	SignalMandatory number known to the provider and telecom layer. [1] [2]	SimpleXMore multi-device friction; relays and notifications require care. [1] [2]
Best suited for	SignalEveryday security; peer-facing pseudonymity with hardened settings. [1] [2] [3] [4]	SimpleXPseudonymous online contacts; minimising account identifiers. [1] [2] [3] [4]
Confidence and scope	SignalScope-limited documentary evidence; production metadata and distributed binaries not experimentally verified. [1]	SimpleXScope-limited documentary evidence; production metadata and distributed binaries not experimentally verified. [1]

Technical details: identity, keys, push, devices, audits and evidence

Property	Signal	SimpleX
Email requirement	SignalUnknown: not established for the version and configuration in question.	SimpleXNot required. [1] [2]
Username / discovery	SignalOptional; no public username directory. [1] [2]	SimpleXNo mandatory global username; optional public address should be avoided for compartmentalisation. [1] [2]
Number visible to contact	SignalCan be hidden: number visibility AND discovery set to Nobody; a number already known to the contact is not forgotten. [1] [2]	SimpleXNo required number to disclose. [1] [2]
Global user ID	SignalService account remains linked to the phone number. [1] [2]	SimpleXNo global user ID required. [1] [2]
Forward secrecy	SignalDocumented protocol property; depends on clients and linked devices. [1] [2]	SimpleXDocumented Double Ratchet; versions and implementations still need verification. [1] [2]
Post-compromise security	SignalCryptographic recovery after temporary compromise; not while spyware remains in control. [1] [2]	SimpleXPost-compromise recovery described by the protocol; requires an uncompromised endpoint. [1] [2]
Key verification	SignalOut-of-band Safety Number; AKV does not certify identity and requires the other account’s number. [1] [2]	SimpleXUnknown: not established for the version and configuration in question.
Relay / TURN	SignalEnable Always Relay Calls when peer IP exposure matters; the relay sees the IP. [1] [2]	SimpleXAlways use relay; TURN sees IP and duration. [1] [2]
What the provider learns	SignalRegistration number and limited account data; not normal E2EE content by design. [1] [2]	SimpleXRelays see their transport data; message bodies are E2EE. Declared non-logging was not measured here. [1] [2]
What the contact learns	SignalThe contact receives messages and the profile you share, and can keep a copy. [1] [2]	SimpleXThe contact receives messages and the profile you share, and can keep a copy. [1] [2]
What the network / ISP learns	SignalThe network sees destinations, timing and volume; Tor or a relay changes the observer. [1] [2]	SimpleXThe network sees destinations, timing and volume; Tor or a relay changes the observer. [1] [2]
Push notifications	SignalExact APNs payload not captured; manage local notification previews. [1] [2]	SimpleXiOS push: queue and frequency data partly visible to the service; exact payload not captured. [1] [2]
Apple / Google exposure	SignalStore, installation and push can create metadata; exact profile linkage depends on the OS and was not tested here. [1] [2]	SimpleXStore, installation and push can create metadata; exact profile linkage depends on the OS and was not tested here. [1] [2]
Groups	SignalUnknown: not established for the version and configuration in question.	SimpleXUnknown: not established for the version and configuration in question.
Calls	SignalDocumented calls; their network path must be distinguished from messaging. [1] [2]	SimpleXDocumented calls; their network path must be distinguished from messaging. [1] [2]
Backups	SignalUnknown: not established for the version and configuration in question.	SimpleXLocal profiles and history; complete version-specific backup guarantees not established here. [1] [2]
Source code and binaries	SignalRepositories and component-specific scopes recorded in Phase 2; no current binary rebuilt bit-for-bit here. [1] [2]	SimpleXRepositories and component-specific scopes recorded in Phase 2; no current binary rebuilt bit-for-bit here. [1] [2]
Audits	SignalProtocols and AKV examined under distinct scopes; not the whole infrastructure or every binary. [1] [2] [3]	SimpleXTrail of Bits 2022 and 2024 protocol review; announced 2026 review had no usable public report at the research cutoff. [1] [2] [3]
Public law-enforcement evidence	SignalPublished 2026 provider response: creation and last-connection dates for six accounts; not messages. [1] [2] [3]	SimpleX2025 provider claim: 12 requests with no responsive information; no independent court dossiers. [1] [2] [3]
iOS	SignalYes, client listed in the study. [1] [2]	SimpleXYes, client listed in the study. [1] [2]
Android	SignalYes, client listed in the study. [1]	SimpleXYes, client listed in the study. [1]
Windows	SignalYes, client listed in the study. [1] [2]	SimpleXBeta; desktop-specific limits. [1] [2]
macOS	SignalYes, client listed in the study. [1] [2]	SimpleXBeta; desktop-specific limits. [1] [2]
Linux	SignalYes, client listed in the study. [1] [2]	SimpleXBeta; desktop-specific limits. [1] [2]
Avoid if…	SignalYou refuse to give a number to the service. [1] [2] [3] [4]	SimpleXYou cannot accommodate profile, relay and local-pairing constraints. [1] [2] [3] [4]
Recommended configuration	SignalVisibility and discovery: Nobody; fresh username, neutral profile, verified Safety Number, relayed calls when needed. [1] [2] [3] [4]	SimpleXFresh profile, single-use invitation, no reused identity; TURN; deliberate iOS notification choice. [1] [2] [3] [4]
Remaining unknowns	SignalCurrent network behaviour, distributed binaries and forensic evidence remain incomplete; check version, OS and configuration. [1] [2]	SimpleXCurrent network behaviour, distributed binaries and forensic evidence remain incomplete; check version, OS and configuration. [1] [2]
Ease of use	SignalVery practical for iPhone + PC; the primary phone remains necessary. [1] [2] [3] [4]	SimpleXMore setup and friction than Signal; local pairing. [1] [2] [3] [4]
Network anonymity	SignalNo general resistance to a global passive observer is demonstrated. [1] [2]	SimpleXNo general resistance to a global passive observer is demonstrated. [1] [2]

Customise this comparison

• Compromised / unlocked device and spyware.
• Copying, screenshots or disclosure by the contact.
• Initial Discord traces, reused alias, avatar, voice or files.
• Global correlation; relay, ISP, telecom, store and backup data depending on the path.