Signal is an open-source encrypted messaging application with end-to-end encryption by default, developed by the Signal Foundation (nonprofit).
What Signal collects: only your phone number and registration date. Not message content, not who you message, not when. Confirmed in multiple legal proceedings where Signal was subpoenaed and had nothing to provide.
Signal’s encryption protocol is the strongest available for messaging, adopted by WhatsApp and others, though those applications collect significantly more metadata.
Limitation: requires a phone number to register. For situations where the number itself must not be associated with an identity, combine with additional OPSEC measures.
What it means in practice
Signal encrypts messages end-to-end and stores minimal metadata. Disappearing messages should be enabled for all sensitive communications — message history that does not exist cannot be seized, subpoenaed, or used against contacts. Signal works in intermittent connectivity, queuing messages until the connection returns. For NGO field workers and journalists, it is the baseline for source and field communications, not an optional upgrade.
Related articles
How to communicate with confidential sources safely. — A journalist was arrested because of an email. — How to secure communications in the field. — Digital privacy guide for NGO workers abroad.