This app is discontinued and removed from all distribution channels.
WebSMS is a simple app allowing you to send text messages to anybody via different kinds of web services. The recipient does not need any app. The text messages is sent to the recipient as default text message / SMS. The integration with these web services is done by so called WebSMS Connectors.
Check out the FAQ.
Help to translate the app on crowdin.
Documentation about creating a connector is hosted within the websms-api project.