Which developer created the mobile game Pokémon GO?

Niantic created Pokémon GO.

Pokémon GO is a 2016 augmented-reality mobile game developed and published by Niantic in partnership with Nintendo and The Pokémon Company. It uses GPS and a mobile device's location data to place Pokémon in the player's surrounding world.

The game launched first in Australia, New Zealand, and the United States on July 6, 2016, before expanding to additional countries. Players can find, capture, train, and battle Pokémon while moving through real-world locations.

Niantic had previously developed location-based technology through Ingress, which helped inform Pokémon GO's map-based structure. Game Freak developed the main Pokémon role-playing games, but it was Niantic that developed this mobile augmented-reality title.