Generate fake data

I see https://blog.couchbase.com/fakeit-series-generating-fake-data/
fake it (https://www.npmjs.com/package/fakeit) is out of date

Is there any build in tools to gerenate data?

Not sure if that is what you are looking for, but check out the cbworkloadgen tool https://docs.couchbase.com/server/6.0/cli/cbworkloadgen-tool.html, it might serve your needs.