A project I'm using, which I'm also one of the authors of, is OctoSQL[1].
It allows you to transform and join data from different data sources (including databases like mysql, postgres, redis, and CSV or JSON files, more to come) using a familiar interface - plain SQL.
Other than that, I like Exploratory[2].
And for nested JSON data I use another project of mine, jql[3] - an easier to use (in my opinion) lispy alternative to jq. (originally inspired by a hackernews comment actually)