> ## Documentation Index
> Fetch the complete documentation index at: https://docs.privy.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Overview

> Sponsor transaction fees across all wallets using the Privy gas sponsorship engine.

Privy's **gas sponsorship** engine gives you flexible control over how transaction fees are paid across your wallets. Privy supports two modes:

* **App pays** — your app's gas credits cover fees for all users. Users transact without ever needing to hold ETH or native tokens.
* **User pays** — gas fees are covered using the wallet's USDC or USDT balance, with no ETH required. Your app's gas credits are not charged.

<Info>
  Ready to get started? See the [setup guide](/wallets/gas-and-asset-management/gas/setup).
</Info>

<img src="https://mintcdn.com/privy-c2af3412/xvj7sxQ8SLxi5bGo/images/gas-management-splash.png?fit=max&auto=format&n=xvj7sxQ8SLxi5bGo&q=85&s=ef0ae9ef9ea08a2f600e896cdec746b9" alt="gas management splash" width="3686" height="2633" data-path="images/gas-management-splash.png" />

## Supported networks

<Tabs>
  <Tab title="App pays">
    App pays sponsorship is available on all of the networks below.

    <AccordionGroup>
      <Accordion title="Ethereum networks">
        **Mainnets:**

        * Ethereum
        * Base
        * Optimism
        * Polygon
        * Arbitrum
        * BNB Smart Chain
        * Unichain
        * Gnosis
        * Plasma
        * Berachain
        * Warden
        * Flow
        * Fluent
        * Edge
        * Monad
        * World Chain
        * Story
        * Ronin
        * MegaETH
        * Ink
        * Shape

        **Testnets:**

        * Sepolia
        * Base Sepolia
        * OP Sepolia
        * Polygon Amoy
        * Arbitrum Sepolia
        * Unichain Sepolia
        * MegaETH Testnet
        * Ronin Saigon
        * Monad Testnet
        * Ink Sepolia
        * Fluent Testnet
        * Edge Testnet
        * Robinhood Testnet
        * Shape Sepolia
      </Accordion>

      <Accordion title="Tempo networks">
        **Mainnets:**

        * Tempo

        **Testnets:**

        * Tempo Testnet
      </Accordion>

      <Accordion title="Solana networks">
        **Mainnets:**

        * Solana

        **Testnets:**

        * Solana Devnet
      </Accordion>
    </AccordionGroup>

    Want support for more networks? [Reach out to us!](mailto:sales@privy.io)
  </Tab>

  <Tab title="User pays">
    User pays (token gas) is supported on the following EVM chains only. Solana is not supported.

    | Chain                      | USDC | USDT |
    | :------------------------- | :--: | :--: |
    | Ethereum                   |   ✓  |   ✓  |
    | Base                       |   ✓  |   ✓  |
    | Optimism                   |   ✓  |   ✓  |
    | Arbitrum                   |   ✓  |   ✓  |
    | Polygon                    |   ✓  |   ✓  |
    | Sepolia (testnet)          |   ✓  |   ✓  |
    | Base Sepolia (testnet)     |   ✓  |   ✓  |
    | OP Sepolia (testnet)       |   ✓  |   —  |
    | Arbitrum Sepolia (testnet) |   ✓  |   —  |
    | Polygon Amoy (testnet)     |   ✓  |   —  |
  </Tab>
</Tabs>

## How it works

<Tabs>
  <Tab title="App pays">
    ### Ethereum and EVM chains

    Privy leverages [EIP-7702](https://eip7702.io/) with **paymasters** to sponsor gas fees:

    * User wallets are upgraded to smart contracts
    * Paymasters cover gas costs automatically
    * Users can transact immediately without holding ETH or native tokens

    <Info>
      **Native gas sponsorship vs smart wallets**

      Our [smart contract wallets](/wallets/using-wallets/evm-smart-wallets/overview) offering
      creates a separate 4337-compatible contract account, where the embedded wallet is the signer.

      Native gas sponsorship lets you:

      * Sponsor gas for embedded wallets without creating a separate contract account
      * Get set up without managing extra bundler or paymaster providers
      * Use a simpler developer experience — just pass `sponsor: true`

      *If you already have users with funds in smart contract wallets, we recommend continuing to
      use smart contract wallets.*
    </Info>

    ### Tempo networks

    For Tempo transactions (type 118), Privy uses Tempo's native fee-payer signature flow:

    * Privy adds `fee_payer_signature` to the Tempo transaction before broadcast when `sponsor: true`
    * This flow is native to Tempo and does not use ERC-4337 user operations, EIP-7702 wallet upgrades, or EVM paymasters, reducing overhead for faster transactions

    <Info>
      Learn more about Tempo's native fee sponsorship in the [Tempo transaction
      specification](https://docs.tempo.xyz/protocol/transactions/spec-tempo-transaction#fee-payer-signature-details).
    </Info>

    ### Solana and SVM chains

    Privy uses a **fee payer wallet** to cover transaction costs:

    * A Privy-managed fee payer wallet funded with SOL covers fees
    * The fee payer updates the transaction's `feePayer` field and latest blockhash
    * Users transact without needing to hold SOL

    ### Calculating gas fees

    Privy automatically handles gas fee calculation and optimization. Gas sponsorship includes the
    actual network gas cost plus a convenience fee for the managed service.

    <Info>
      Looking for more granular control over gas pricing? Consider exploring [custom
      setup](/wallets/gas-and-asset-management/gas/ethereum) options.
    </Info>
  </Tab>

  <Tab title="User pays">
    When a user initiates a transfer, Privy:

    1. **Gets a gas quote** from the Alchemy ERC-20 paymaster to estimate the maximum fee
    2. **Checks the wallet balance** — verifies the wallet holds enough to cover both the transfer amount and the estimated gas fee
    3. **Submits the transaction** — a paymaster approval is bundled atomically with the transfer
    4. **Paymaster collects the fee** — after execution, the paymaster collects the exact gas fee from the wallet's USDC or USDT balance.

    The gas token is always the same as the token being transferred. For example, when a user sends
    USDC on Base, the gas fee is also deducted in USDC — no ETH is required.
  </Tab>
</Tabs>