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Universal Paymaster Pattern

The VelumX architecture is built on the Universal Paymaster pattern, a paradigm shift in blockchain ergonomics that decouples transaction intent from fee settlement.

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Conceptual Overview

In traditional blockchain interactions, the transaction originator must also be the gas payer. This requirement creates a “chicken-and-egg” onboarding problem: users need native tokens to interact with the network, but often arrive with non-native assets. VelumX resolves this by leveraging the Stacks native Sponsored Transaction capability.

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Technical abstraction

The Paymaster acts as a secure intermediary. While the user signs the transaction “intent” (e.g., a swap or a bridge), the VelumX Relayer adds a secondary sponsorship signature and settles the STX gas fee.

Native Abstraction

Uses Stacks-native sponsorship flags, requiring zero custom smart wallets or complex ERC-4337 style bundlers.

Asset Agnostic

Enables users to settle infrastructure fees in any supported SIP-010 token, such as USDCx, sBTC, or ALEX.

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Interaction Flow

The Paymaster pattern follows a strict “validate-then-execute” lifecycle:
  1. Authorization: The user authorizes a small fee transfer to the Relayer within the same atomic transaction as their primary action.
  2. Sponsorship: The Relayer verifies the intent and the user’s balance, then signs for the STX fee.
  3. Atomic Execution: On-chain, the transaction settles the fee to the Relayer and executes the user’s business logic simultaneously. If either step fails, the entire transaction reverts.