My friend needed to send credit-card data to a client and couldn't find a widely available program for sending password-protected files. So, I wrote one. This webpage encrypts a file and packages it into an HTML file, which contains JavaScript code to accept a password and decrypt the data. The code uses the Web Cryptography API and works with every major browser released since 2015.<p>I'd love feedback. Especially from experts on cryptography and the Web Cryptography API.