Open it from the Selection Wheel or feature bar in game (or bind it a key in Overlays → Hotkeys), or open Workbench → Item Database in the app. It is the complete list of item bases and uniques with the modifier pool each one can roll, and it works with no network connection.
What it answers
"What can this base roll?" Pick a base and you get its full mod pool: every prefix and suffix, each tier, the numeric range per tier, and the item level that tier requires. This is the lookup that decides whether a craft is possible before you spend anything on it.
"What base should I be looking for?" Work backwards. If you need high flat life and a specific resistance in one slot, the database tells you which bases can carry both, and which implicit you would be giving up.
"Is this unique worth it?" Uniques have fixed modifiers and rolled numbers. The database shows the ranges, so you can tell a well-rolled copy from a floor-roll one — and tell which uniques even have a roll worth chasing.
"What item level do I need?" Tier requirements are listed per tier. This is the number that goes into your trade search and the number that makes a cheap base worthless.
Practical uses
Before buying a crafting base. Two minutes in the database saves the "ilvl 74 base cannot roll the mod I wanted" discovery you would otherwise make after spending the currency.
While pricing an unfamiliar item. If you do not know whether tier 3 is good for a given mod, look up the pool. Tier 3 of eight is different from tier 3 of four.
When building a trade search by hand. The database gives you the real mod names and the ilvl gates, which is what the Trade Link Builder then turns into a search.
Planning a league start. Knowing which bases carry which implicits lets you decide what to pick up and what to leave on the floor before prices exist.
How it relates to the other tools
The price panel's Modifier Overview tab is the same data, scoped to the item you are holding — use that when you have the item and this when you do not.
The Crafting Assistant filters this pool down to what is *still possible* on a specific item in its current state. The database shows the whole pool regardless.
The offline part matters
This data is bundled with the app. It does not need your Path of Exile session, an ePOE account, or an internet connection. Two consequences worth knowing:
- It works when GGG's API is rate-limiting you or down, which is exactly when you want a reference.
- It is only as current as your app version. After a patch that changes mod pools, update ePOE before trusting a tier range.
You can pop it out as its own always-on-top window over the game from the wheel, the feature bar or a hotkey of your choosing, which is the intended way to use it: the item in your stash, the pool next to it, no alt-tabbing.