Top 5 Free Chess Databases

I have been playing chess a lot recently on chess.com and I'm thinking about buying a subscription. I know the diamond is the best one as is it the most expensive but

learning - Where can I find free training tools like detailed annotated chess openings, middle games and endgames in the PGN format? - Chess Stack Exchange

Zarkon Fischer's Free Chess Programs: SCID 4

Arena Chess GUI

The Best Chess Apps for Kids and Chess Lovers

What are the best chess apps for Android? - Quora

Best Chess Apps and PC Software for Playing and Training - TheChessWorld

Mega Database 2023

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Chess Database with Master Chess Games