[kentonv]

There's no hard limit, but given that a single durable object is single-threaded, storing a huge amount of data in a single object may make it hard to access that data. Also, the system may be less likely to migrate huge objects to move them closer to their users. So, we recommend aiming for small, fine-grained objects, kilobytes to megabytes in size. But there's nothing fundamentally preventing an object from growing to multiple gigabytes.