The Fuel GraphQL API allows you to query the Fuel blockchain for a wide range of on-chain data. It can be used to query transactions, balances, block information, and more. You can also use it to simulate and submit transactions on the Fuel network.
The playground is an interactive and graphical IDE that includes a reference for queries, mutations, and types. It also provides query validation and context for the underlying GraphQL schema.
You can test out the Fuel GraphQL API playground here:
Beta-4: https://beta-4.fuel.network/playground