Armor
Classes
Conflicts
Ethos
Flaws
Glossary
Kits
Maleficence
Origins
Shields
Skills
Spells
Stances
Status Effects
Tactics
Talents
Techniques
Treasure
Weapons
Save yourself time in prep. The tools you select to help you worldbuild shouldn't get in your way by posing huge learning curves or generate opinionated content that won't be flexible enough to gel with your campaign.
Random Tables
You want to embrace (tailored) randomness whenever possible, and especially if it will save you session prep time.
OSR+ runs on the d6, so when you design random tables on the fly, a little table of six to twelve options is an optimal, player-facing choice for a little injection of the unknown.
However, as a GM, you likely have the whole suite of dice at your disposal. There are countless system-agnostic random generators online to choose from (the oldie but goodie Donjon website for example has tons of random table generators), as well as meaty texts like the Tome of Adventure Design, written expressly for this purpose.
If you don't know the answer to what the environment contains when a player asks, why not reach for a random table to surprise yourself?
Map Generators
You can certainly hand-draw the world map if it brings you joy, but if you want to save time, some of the tools below will generate completely random maps containing everything from names of continents to population statistics.
Browser-based SaaS
These software-as-a-service maps let you design in the browser. Inkarnate is more geared toward designing world maps, whereas Dungeon Fog is better for designing battle maps and dungeons. Don't forget Dungeon Scrawl, which is free and can do isometric maps. Finally, randomizers like the legendary Azgaar's Fantasy Map Generator and Watabou's series of impressive, randomly-generated map-making tools are both free and run in the browser.
2d Local Software
If you want to purchase map-making software to use locally, Wonderdraft (for world maps) and Dungeondraft (for battle maps and dungeons) by Megasploot provide a more modern UI and integration with popular VTTs. The pricier Campaign Cartographer, while being a much older and clunkier software, offers a massive history of extensible content with multiple flavors of programs (including scifi). Lastly, the more free Hexographer series of map making tools may look early 2000s-era but can also get the job done.
3D Local Software
For the high-tech GM, a number of incredible tools exist for randomly generating 3D dungeons. Dungeon Alchemist and Chronos Builder (which has more non-fantasy genres) are relatively new to the market and run on your computer, but can export both 2D and 3D maps.
Hall of Heroes
Hall of Legends
Dungeons & Flagons