Battlefield 1, developed by EA DICE and published by Electronic Arts, uses the Frostbite 3 engine. Frostbite has been used to power numerous titles across various genres from EA, including the Battlefield series, FIFA series, and Dragon Age: Inquisition among others.
This technology is lauded for its impressive visual capabilities, realistic physics, dynamic environments, and destruction system. It's not freely accessible to independent developers unlike some other engines like Unity or Unreal Engine, as it's kept for internal use by studios under the EA umbrella.
Please note that while Frostbite provides a foundation for building games, developers need to create or tailor additional code and tools to meet the specific needs of each individual game project. This can include elements like unique gameplay mechanics, AI behavior, and more.