PF GMs, which books do you allow?

As someone who has DMed Pathfinder in person, with the books I happen to have, and sometimes stuff found online through OGL, I'm curious what PF DMs on here tend to allow. Do you just use core rules (Core Rulebook, maybe Bestiary races and APG stuff)? Do you allow everything, and just have players seek out the information? Or is it somewhere in the middle?

I'm curious, because as a DM, allowing technically everything got messy for me, and as a player, I think I'd enjoy having options, but I'd be overwhelmed by "pick from EVERYTHING." the Core Rulebook and Advanved Player's Guide already have tons of choices alone.

For me, I accept any book from Paizo when running a Pathfinder game (mostly because I have much of their material in print, and it's basically all available online from their PRD). Also, with my style of GMing, I don't really fret about game balance between characters. I do, however, reserve the right to refuse anything that looks like an exploit.

However, many games run here do put bounds on source material, so limiting to CRB+APG wouldn't be an abnormal approach.

I guess it depends on the game that I run. Last PF game I ran was a conversion of D&D 3.5's Expedition to Castle Ravenloft. And since the adventure made heavy use of elements found in Libris Mortis and also had it's own prestige class.Because of that, I was sort of forced to allow pretty much anything under the caveat that I must have a look at it first and then that I must approve it.

I run one PF 1e game here, and I use the CRB+APG plus some additional options (Magus from Ultimate Magic, Unchained rogue). Mostly because that’s what I know, not because I’m worried about game balance (though that is a secondary concern). The way the game has worked, it hasn’t been really necessary to limit — it’s more RP heavy — but it keeps me sane. Sane-ish.

My rule is "As few as possible". Core book, a single bestiary, and the Gamemastery Guide. Pathfinder is great in that the game is robust enough that you don't need anything beyond these three. Two books I find that add a lot without encouraging min/maxing are Ultimate Equipment, and Ultimate Campaign. The latter is, in my opinion, just a great RPG book in general.

I've never restricted my books, but if I ran it again, I'd probably do:

Core Rulebook
Advanced Player's Guide
Ultimate Magic
Ultimate Combat
Ultimate Equipment
Ultimate Campaign

This would allow a LOT of choices without making it impossible to sort through it all

Anything that appears on the PRD that isn't third party! I do permit some 3P stuff, but not all. My personal campaign, for example, has gearforged, uses the feat tax rules, and utilizes the Book of Distinctions and Drawbacks by Cryptosnark Games.

I accept any book or non-book concept BUT with a caveat it may not come across as written as I will balance it to what is in the basic book -- and I have a solid way of doing this and I have done it numerous times to help someone build the character class they are wanting to play regardless if that class is actually existent of not.

Still if I were a beginner just the basic PHB and DMG and no more. It all has to do with your comfortability with the guidelines and your ability to balance classes against classes. Just keep in mind, your job as a GM is not to restrict your players but maintain balance between them such that you do not have a Batman playing along side a Superman.