Live Nations
According to the Montevideo Convention, in order to be considered a state, you must have the capacity to enter into relations with the other states.
Originally Live Nations was started in order to help diplomatically active nations and micronations meet the Montevideo Convention requirement. Nations that are members of Live Nations have to provide detailed, no nonsense information about their nation, the nation's incorporations, and must also show periodic evidence that they are still active.
Today Live Nations membership seekers must provide evidence of meaningful international recognition, realism (several active incorporations or agencies), and complexity.
There is only one nation thus far which qualifies for Live Nations membership, due to its international recognition, realism, and complexity. That nation is the United Micronations Multi-Oceanic Archipelago (UMMOA).
However, Live Nations membership is open to any nation with a similar level of recognition, realism, and complexity.