They're SaaS and I believe they do have a webpack plugin (I used their grunt plugin). The plugin will send your code to their servers and wait for it to come back.
Not sure what exactly they're promising wrt. the quality of obfuscation, but if it actually works "well enough" you'd imagine they should be happy for you to run an obfuscated version of their code[1] rather than shipping your JS to their servers. Hmm... :)
[1] I'm assuming it's written in JS. It might not, of course.
There's also an on-premises version, if you don't want to send your code elsewhere..but I guess it might need a bit of investment..