Steam knows half your achievements. PlayStation knows the rest.
AchieveAll pulls both into one profile, along with Xbox, RetroAchievements and Riot. Then it scores everything by how rare the unlock actually is, so a 0.2% trophy counts for more than finishing a tutorial.
Plus a feed, game communities, and a profile you'd actually want to link.
Why this exists
I hunt on Steam and PlayStation, and for years my achievements lived in two separate places that had no idea about each other. Merging them was the obvious first thing to fix.
The part I actually cared about came after. Achievement sites are mostly databases: rows of numbers, nowhere to ask how someone managed the 0.3% trophy you've been stuck on for a month, and no profile page worth pasting anywhere. Hunting is a social hobby that ended up with very little social software.
So AchieveAll does both. It links your accounts and weights every unlock by how rare it really is, and then it puts a feed, per-game communities and a profile you can make your own on top of that.
It's a small site and I'm still fixing things. The feedback button on every page goes straight to my inbox, and I read all of it.
— Sergiu, JackyGodLvL on Steam