Encrypt.to is a web application designed to facilitate the sending of encrypted PGP messages. It allows users to send encrypted messages to recipients who have their public keys stored on a public keyserver or uploaded to the service.

The primary problem it solves is the complexity of sending encrypted PGP messages. Users can send encrypted messages without needing to manually encrypt the message or manage their public keys.

The target users are individuals who want to send encrypted messages to others. The service is particularly useful for those who are not familiar with PGP encryption or do not want to deal with the technical aspects of it.

The application works by allowing users to upload their public keys to the service or use keys stored on a public keyserver. When a user sends a message, the service encrypts the message using the recipient's public key and sends it to the recipient.

Notable patterns include the use of the Ruby on Rails framework, the integration with the Stripe payment processor, and the use of the Devise gem for user authentication. The application also includes a number of security features, such as the ability to set a password for the message and the ability to set an expiration date for the message.