There are others available, but most don’t include a CLI, or easily configurable options. Many use small word lists. So I made one that uses a sufficiently large list—113,809 words provided by the Moby Project—and both a simple commandline utility and a module that you can use in your Node.js apps. If you don’t like my wordlist, you can substitute your own easily. Everything is non-blocking, so you shouldn’t find it bogging down your stuff.
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Usage: xkcd-password [options] Options: -n, --numWords The number of words to generate for your password.  -m, --minLength Minimum lengh of words chosen for the generated password.  -x, --maxLength Maximum length of words chosen for the generated password.  -f, --wordFile The newline-delimited list of words to be used as the source. -s, --separator The separator character to use between words when output to the console. [ ] --version print version and exit