PumperTaxHook

Base

PumperTaxHook is a Uniswap v4 hook on Base. Runs code on every swap. Can take tokens from swaps. Sets its own swap fee.

Contract name: PumperTaxHook

0x45173eb5c16a6360d4693b4b2678ca617d0580cc First pool 9 Nov 2026View on explorer

Launch a pool with this hook

CBe carefulNot in Uniswap’s hook registry · Can take tokens out of swaps?

Pools

Last new pool

Code size

2,391 B

How this hook works

Trading tax

A trading tax hook. It sets its own trading fee and takes a tax on trades.

Sets its own trading fee

Instead of a fixed fee chosen by the pool creator, it decides the fee itself on each trade.

The code that does this (beforeSwap):

function beforeSwap(address, PoolKey calldata key, SwapParams calldata params, bytes calldata)
    external
    returns (bytes4, BeforeSwapDelta, uint24)
{
    if (msg.sender != address(poolManager)) revert NotPoolManager();
    if (params.amountSpecified > 0) revert ExactOutputNotSupported();

    bool isBuy = _isBuy(key, params);
    if (!isBuy) {
        return (this.beforeSwap.selector, BeforeSwapDeltaLibrary.ZERO_DELTA, LPFeeLibrary.OVERRIDE_FEE_FLAG);
    }

    uint256 gross = uint256(-params.amountSpecified);
    (uint256 fee,) = PumperFeeMath.quoteFeeFromGross(gross, uint256(buyTaxBps + BASE_FEE_BPS) * 100);
    BeforeSwapDelta delta = toBeforeSwapDelta(int128(int256(fee)), 0);
    return (this.beforeSwap.selector, delta, LPFeeLibrary.OVERRIDE_FEE_FLAG);
}

Takes a tax on trades

On top of the normal pool fee, it keeps part of each trade as a tax. Buys and sells can be taxed differently.

The code that does this (beforeSwap):

function beforeSwap(address, PoolKey calldata key, SwapParams calldata params, bytes calldata)
    external
    returns (bytes4, BeforeSwapDelta, uint24)
{
    if (msg.sender != address(poolManager)) revert NotPoolManager();
    if (params.amountSpecified > 0) revert ExactOutputNotSupported();

    bool isBuy = _isBuy(key, params);
    if (!isBuy) {
        return (this.beforeSwap.selector, BeforeSwapDeltaLibrary.ZERO_DELTA, LPFeeLibrary.OVERRIDE_FEE_FLAG);
    }

    uint256 gross = uint256(-params.amountSpecified);
    (uint256 fee,) = PumperFeeMath.quoteFeeFromGross(gross, uint256(buyTaxBps + BASE_FEE_BPS) * 100);
    BeforeSwapDelta delta = toBeforeSwapDelta(int128(int256(fee)), 0);
    return (this.beforeSwap.selector, delta, LPFeeLibrary.OVERRIDE_FEE_FLAG);
}

Who controls it: No admin functions: nobody can change its rules after deployment.

Based on the hook’s published code.

Safety report

Before you build on it. Automated checks, not an audit

5 to review3 passed1 info1 unknown

Contract

✓Code is fixedNo proxy, so the code that runs today is the code that runs tomorrow.

✓No admin key foundIt has no owner wallet, so the hook developer has no single key to change its rules (as far as the standard check goes).

✓Source code publishedThe code on the block explorer matches what's deployed (contract: PumperTaxHook).

Pools3 to review

!Pools don’t trade in Uniswap’s app yetIt runs code on swaps, so Uniswap’s app only routes it once Uniswap Labs approves it, and it isn’t approved yet. Adding liquidity still works, and other apps can trade it.

!Can reject swapsIt runs on every trade and can block it. Used for things like launch limits and start times.

!Can change swap amountsIt has return-delta permissions, so it can take or add tokens in every trade (taxes, fees, burns, custom curves). Check where that value goes and who controls it.

iControls the swap fee1 of its pools use a dynamic fee the hook sets per trade, so LP income depends on its logic.

Track record2 to review

!Not in Uniswap’s hook registryNot listed by Uniswap Labs, so nobody outside the hook developer has looked at it. Most abandoned and malicious hooks are unlisted.

!Brand newIts first pool was created less than a day ago, so it has no track record. Prefer proven hooks for a real launch.

?No audit linkedNothing in the registry. Ask the hook developer for one or review the source yourself.

What it can do

Runs code on every swap

Its code executes inside each trade in pools that use it.

Can take tokens from swaps

It can take or add tokens during a swap. Fees, burns and custom curves work this way, and so do scams.

Sets its own swap fee

Pools using it let the hook choose the swap fee instead of a fixed tier.

Hook history

Took tax 1 time
Latest transactions
- 0xacc1c796…9893a4 block 55,372,272
See every one on the explorer ↗

Counted from what the hook recorded on-chain across all its pools, for every action in its published code, plus token transfers in and out of it.

Pools

1 total

PairCreatedTrades · 7dPool ID

WETH / MULTI 1h 1 trades · 7d 0xe74f…08e1 Tx ↗