People often talk about writing as a solitary act, or a mysterious process of inspiration. And it can be. But a lot of the time when I’m writing, especially when I’m doing the heavy worldbuilding that goes into making a persuasive speculative fiction, I’m not working entirely alone. I’m drawing on pre-existing tools, materials, and guidelines that help me think about the world in productive and interesting ways. Here are some of the ones I use most frequently. A lot of these resources are supposedly for roleplaying (such as the Kobold Guide to Worldbuilding, a big chewy PDF detailing how to build a fantasy world) but they work equally well for conventional fiction (with minor modifications).
Donjon is a great online resource for a lot of different “randomly generated” things: maps, names, etc. I particularly like their fractal world generator, which produces really sexy-looking world maps. They have name generators related to specific subgenres like science fiction, but it can also be really fun to use those “incorrectly”–give your spacefarer a medieval French name!
Buried Without Ceremony makes lots of interesting games that guide storytelling and worldbuilding experiences, but perhaps none more so than The Quiet Year. The vanilla version is like $6 (you can pay more if you like it) and there’s also a monster-flavored version available for free. You can learn a lot about making a compelling world from playing RPGs generally, but some games are more designed more with storytelling in mind as a goal.
Some basic ideas about researching on the Internet: look for stuff that’s made by nerds, stuff that cites its sources. I’d say to try and avoid things that have an agenda, but since that’s impossible, look for things where the agenda seems to be “oh my god this thing is so neat let me tell you all about it.”
As far as more in-depth research goes, I’m not the best researcher so I often lean on Wikipedia and the sources it cites, only some of which are free on the internet. I also use my university’s library pretty heavily, which gives me access to some things behind paywalls. One of the best pieces of advice I can suggest, when doing research, is to look for projects run by universities or other public institutions that are trying to compile information on a topic for public use–such as this Prices and Wages project by the University of Missouri, or this project about Bohemianism from Mt Holyoke. NASA has a surprising number of free ebooks available, including one on how to run a space station.
But outside of that, there are some good places to find research on the free web. I’ll be honest; the Victorian Web has done more for me than almost any other research source. I’ve spent a lot of time reading little tidbits on there that make it into fantasy stories set in the 19th century. Did you know that the Library of Congress has digital exhibits that you can browse, including architectural guides and old maps? The Public Domain Review is also a fascinating source of images (and some articles) that will provoke and inspire, especially if you’re a fantasy writer. My cover art comes from there, and just happens to look a lot like the cover of a D&D manual.