Unlike Ethereum where https://etherscan.io is the only dominant explorer, TON is a more decentralized ecosystem with different explorers that excel in different things. The full list is on https://ton.app/explorers

Some interesting ones:

• https://tonscan.org - Great for simple things, polished UI. Excellent for users, less for developers.

• https://tonwhales.com/explorer - Good for developers since it shows much more low level information if you need to debug transactions that failed.

• https://dton.io - Also good for developers since shows low level data. Has a very cool feature of transaction tracing which shows the TVM opcode executed in each transaction.

Also notes that the explorers have special versions for testnet. Like https://testnet.tonscan.org

There are many explorers available for TON. You can see them all here:
https://ton.app/explorers

I personally like Tonscan, because it allows you to view smart contract opcodes. It's used by most developers.

dTon is also nice because it also displays some data about the blockchain overall, if you're looking for macro-level data, similar to the Etherscan counterparts.