You can simulate Ethereum transactions on the mainnet with Pelta Shield.
This tool allows you to see the usual tx info (such as what you would see on Etherscan) before the transaction actually gets included in a block.
It can therefore be particularly useful for testing and debugging purposes, as it allows you to see how the transaction would affect the state of the Ethereum blockchain without the need to wait for it to be mined and included in a block.
In fact you can even abort the simulated transactions if you don't like the result of it, and you will not pay any gas.
Note that the results of the simulation will only be accurate as long as the transaction doesn't depend too much on the live state of the Ethereum blockchain.
If the state of the blockchain changes between the simulation and the actual execution, the simulation may not accurately reflect the result of the transaction.
DISCLAIMER: I should mention that I am the founder of Pelta.tech, the startup that developed Pelta Shield, so I'm definitely biased in my recommendation.