Signal vs Threema

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

Property	Signal	Threema
Account identifier	SignalRegistration phone number; optional username. [1] [2]	ThreemaRandom Threema ID; optional phone and email. [1] [2]
Phone required by service	SignalYes, even when hidden from the contact. [1] [2]	ThreemaOptional for discovery. [1] [2]
E2EE	SignalMature E2EE for messages and calls; endpoint security remains crucial. [1] [2]	ThreemaE2EE; properties depend on the client, particularly desktop beta. [1] [2]
Metadata exposure	SignalService knows the number; some account dates were publicly disclosed. [1] [2]	ThreemaID, connection data and optional identifiers; store purchase may link identities. [1] [2]
IP exposure to peer	SignalCalls can be relayed; check the setting and actual network path. [1] [2]	ThreemaCheck calling mode and relay per client and configuration. [1] [2]
Multi-device	SignalPrimary iPhone; official desktops linked through the phone. [1] [2]	ThreemaDesktop 2.0 beta: up to two computers, no PFS; older client depends on the phone. [1] [2]
Main strength	SignalMature content security, adoption and iPhone + PC usability. [1] [2]	ThreemaID without mandatory phone or email; mobile maturity. [1] [2]
Main weakness	SignalMandatory number known to the provider and telecom layer. [1] [2]	ThreemaDesktop beta limits, account data and linkable purchases. [1] [2]
Best suited for	SignalEveryday security; peer-facing pseudonymity with hardened settings. [1] [2] [3] [4]	ThreemaPeer-facing pseudonymity without a mandatory number. [1] [2] [3] [4]
Confidence and scope	SignalScope-limited documentary evidence; production metadata and distributed binaries not experimentally verified. [1]	ThreemaClient-specific properties; no PFS in Desktop 2.0 beta, retest status needs verification. [1] [2]

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

Property	Signal	Threema
Email requirement	SignalUnknown: not established for the version and configuration in question.	ThreemaOptional for discovery. [1] [2]
Username / discovery	SignalOptional; no public username directory. [1] [2]	ThreemaUnknown: not established for the version and configuration in question.
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]	ThreemaNot needed when no number is linked / shared. [1] [2]
Global user ID	SignalService account remains linked to the phone number. [1] [2]	ThreemaPersistent random ID; optional linked identifiers add correlation. [1] [2]
Forward secrecy	SignalDocumented protocol property; depends on clients and linked devices. [1] [2]	ThreemaDesktop 2.0 beta does not support PFS; do not generalise to other clients. [1] [2]
Post-compromise security	SignalCryptographic recovery after temporary compromise; not while spyware remains in control. [1] [2]	ThreemaUnknown: not established for the version and configuration in question.
Key verification	SignalOut-of-band Safety Number; AKV does not certify identity and requires the other account’s number. [1] [2]	ThreemaVerify identity / fingerprint through a separate channel. [1] [2]
Relay / TURN	SignalEnable Always Relay Calls when peer IP exposure matters; the relay sees the IP. [1] [2]	ThreemaCall relay properties must be checked on the client being used. [1] [2]
What the provider learns	SignalRegistration number and limited account data; not normal E2EE content by design. [1] [2]	ThreemaID and connection data; aggregate account-data disclosures are published. [1] [2]
What the contact learns	SignalThe contact receives messages and the profile you share, and can keep a copy. [1] [2]	ThreemaThe 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]	ThreemaThe 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]	ThreemaUnknown: not established for the version and configuration in question.
Apple / Google exposure	SignalStore, installation and push can create metadata; exact profile linkage depends on the OS and was not tested here. [1] [2]	ThreemaStore, 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.	ThreemaUnknown: not established for the version and configuration in question.
Calls	SignalDocumented calls; their network path must be distinguished from messaging. [1] [2]	ThreemaUnknown: not established for the version and configuration in question.
Backups	SignalUnknown: not established for the version and configuration in question.	ThreemaUnknown: not established for the version and configuration in question.
Source code and binaries	SignalRepositories and component-specific scopes recorded in Phase 2; no current binary rebuilt bit-for-bit here. [1] [2]	ThreemaRepositories 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]	ThreemaCure53 and Ibex analyses: distinct scopes; desktop retest status needs verification. [1] [2] [3]
Public law-enforcement evidence	SignalPublished 2026 provider response: creation and last-connection dates for six accounts; not messages. [1] [2] [3]	Threema2025 and H1 2026 reports: aggregate account-data disclosures; not evidence of message-content disclosure. [1] [2] [3]
iOS	SignalYes, client listed in the study. [1] [2]	ThreemaYes, client listed in the study. [1] [2]
Android	SignalYes, client listed in the study. [1]	ThreemaYes, client listed in the study. [1]
Windows	SignalYes, client listed in the study. [1] [2]	ThreemaBeta; desktop-specific limits. [1] [2]
macOS	SignalYes, client listed in the study. [1] [2]	ThreemaBeta; desktop-specific limits. [1] [2]
Linux	SignalYes, client listed in the study. [1] [2]	ThreemaBeta; desktop-specific limits. [1] [2]
Avoid if…	SignalYou refuse to give a number to the service. [1] [2] [3] [4]	ThreemaYou require PFS on Desktop 2.0 beta or network anonymity. [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]	ThreemaDo not link phone or email without need; verify fingerprints and each client’s limits. [1] [2] [3] [4]
Remaining unknowns	SignalCurrent network behaviour, distributed binaries and forensic evidence remain incomplete; check version, OS and configuration. [1] [2]	ThreemaCurrent 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]	ThreemaEstablished mobile client; desktop experience remains beta and limited. [1] [2] [3] [4]
Network anonymity	SignalNo general resistance to a global passive observer is demonstrated. [1] [2]	ThreemaNo 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.