I'm not 100% sure that there's a good, free, open source alternative, if that's what you're looking for. The closest you are likely to find is Orange, a data mining and visualization tool. For a little bit of instruction, just do a little Googling, or consult helpful Youtube videos such as the one linked.
If you're willing to pay for it, I would highly recommend using Tableau. They have a free version, called Tableau Public, which only works with flat files, but will allow you to do some basic testing. The licensed version allows native connections to many databases, including Postgres. Lastly, if you are a larger enterprise client who has a business model which permits cloud storage, Chartio may also be a good alternative.
Full disclosure: I have no business connections to any of the companies mentioned, and my post is meant to be purely informative and non-promotional for the companies listed.