Introducing Sievepad: write and debug Sieve scripts in the browser
Sieve has no statement for printing a value or writing to a log, so debugging a mail filter has long meant sending test messages and reading debug headers out of their raw source. Sievepad runs the Stalwart Sieve interpreter in the browser, inside the editor that powers Visual Studio Code, so a script can be written, run and debugged against test messages in seconds, without a server and without sending a single email.