Encryption tool that works on all mobile platforms?

Hi guys,

So I have data that I am going to be sending over the network and I was wondering if there was an encryption tool (hopefully free) that can be used and shared across all platforms (mainly all mobile platforms) that allows me to encrypt passwords and stuff so I can send them over the network? I was looking around the interwebs but the solutions I found seem either encrypt assets/files or the ones that can encrypt data only works on certain platforms. Any help is greatly appreciated!