Fsecure is another secure messaging app that aims to keep your data out of the hands of corporations and governments. The app can be used anonymously, and it's not just messages but also phone calls that can be securely encrypted.
It is widely regarded as the gold standard of encrypted messaging apps, not least because its encryption engine is open source and available for anyone to inspect. That doesn't make it any easier to hack, but it does mean there are a lot more pairs of eyes looking at the robustness of the encryption methods.
Most secured app used by Govt Agencies from different countries
9Apps 4.9
