Relayers
A relayer submits a blockchain transaction for someone else. The user signs an instruction. The relayer sends it to the network and pays the gas. An app can then pay the fee for its user or charge the user in another way.
I worked on the business side of this product at Biconomy. I did not write the relayer. My part was helping applications decide whether to use it, supporting their integration, and carrying technical questions to the engineers who owned the system.
The product removed one small but common demand on a user: acquire the network’s gas token before doing anything else. Removing that step from the screen did not remove the underlying work. Someone still had to submit the transaction, fund the account that paid for it, set limits, watch failures, and answer the application using the service.
Relayers later became one part of the broader account abstraction stack. Smart accounts and bundlers changed the interface and gave applications more control over transaction rules. They did not erase the same operating questions: who submits, who pays, what limits apply, and what happens when a transaction does not land.
This is why I think of gasless transactions as infrastructure, not magic. The cost and responsibility move. They do not disappear.