Martial Archetypes for fighters

I was building a fighter character when I came across the shield-bearer martial archetype, i was hoping for some clarification whether or not this is homebrew or official. If so which book has this archetype so I can buy it

It's homebrew. There's no official option called shield-bearer.

The official ones are arcane archer, battle master, cavalier, champion (the free one), eldritch knight, purple dragon knight, and samurai.

DDB also suports the UA Brute and the CR Gunslinger.