Blog Post

Crypto Sniper Bot Demystified

June 21, 2025

In the world of decentralized finance (DeFi), speed equals profit. And few tools embody that principle better than sniper bots. These bots are designed to front-run new token launches, grabbing assets within milliseconds after they hit the blockchain — often before regular users even see them.

In this post, we’ll break down:

What crypto sniper bots are
How they technically work (step-by-step)
Real examples from Ethereum & BSC
Detection techniques and potential mitigations

⚙️ What Is a Crypto Sniper?

A crypto sniper bot monitors new token listings (typically on decentralized exchanges like Uniswap or PancakeSwap) and automatically executes a buy transaction the moment the token becomes available. The goal? Buy cheap before price discovery begins — then dump on slower users for profit.

They’re often used in:

IDO/ICO launches: Buy in the first block
Liquidity pool launches: Snipe before price skyrockets
Meme coin pumps: Catch the hype wave before it crashes

🔍 Real-World Example

Here’s an infamous example from the Ethereum.

We leveraged AnChain.AI SCREEN platform , to analyze the Internal Transaction of the Crypto Sniper Bot.

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Token: $SWAP (TrustSwap Token)

Liquidity added: Block 10426750
Sniper bot transaction: Executed 12 transactions later in the same block
Bot bought: 1,861.419.7 SWAP for 90 ETH
Dumped: over in multiple swaps over the next 30 minutes
Sold for a 300 ETH profit

Etherscan TXs:

Initial Liquidity Add to Pool: 0xbc8ccdcba34a4ae49197c5ec290067d1e4fb9910c00bbb880340f907dc8d0be6

Snipe Transaction:

0x68acfe8089850cab6fdbd7e48a3a58835f785e427a0d3540684b8d3242cb68bf

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How did the bot win?

It monitored PairCreated events from Uniswap V2 Factory
Monitored the Ethereum mempool
Executed their swap in the same block liquidity was added to the pool

Internal Transaction of the Crypto Sniper Bot, revealed by AnChain.AI SCREEN platform.

🛠️ How Sniper Bots Work (Step-by-Step)

Monitor Factory Contracts
The bot listens for new liquidity pairs being created:

event PairCreated(address indexed token0, address indexed token1, address pair, uint);

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Check Target Token
Apply heuristics:
- Token has verified source code?
- Liquidity added > threshold?
- Creator wallet match a whitelist?
Build Swap Transaction
Prepare a swapExactETHForTokens() or custom router.call() payload.
Snipe on First Block
Use pendingTransactions subscription via WebSocket + mempool:
Bribe Miners / MEV
Send a bribe via gas tip (EIP-1559 or raw gas war). Some advanced bots use Flashbots to avoid frontrunning by other bots.
Auto-sell
Pre-program a dump strategy

🧠 Key Features of a Crypto Sniper Bot

🚦 Mempool Scanning
Reads unconfirmed transactions before they're mined — acting faster than the public mempool.
⚡ Auto Gas Adjust
Dynamically increases gas fees to front-run other buyers and ensure priority execution.
🛡️ Anti-Rug Logic
Detects risky token behavior:
- Honeypots
- Sell-block restrictions
- Malicious tokenomics
💰 Flashloan Boost
Leverages flashloans to maximize buying volume without upfront capital.
📦 MEV Bundles
Submits private transaction bundles via Flashbots — avoiding public front-runs and increasing stealth.

‍

🧪 Real Bot Code Snippet

Example of building a snipe TX:

tx = router.functions.swapExactETHForTokens(
    0,
    [WETH, target_token],
    bot_wallet,
    int(time.time()) + 120
).buildTransaction({
    'value': w3.toWei(0.5, 'ether'),
    'gas': 300000,
    'gasPrice': w3.eth.gas_price,
    'nonce': nonce
})

‍

This simple snippet forms the backbone of many sniper bots, combined with fast monitoring and optional MEV relays.

🕵️‍♂️ Can You Detect a Sniper?

Yes — to a degree.

Detection Signals:

TX in same block as liquidity add
Buy is <1 second from pool creation
Non-human gas patterns (e.g. gasPrice = 777 gwei)
Frequent transactions from a single wallet across many token launches

🧰 Tooling: Platforms like AnChain.AI, and similar can spot these anomalies in bulk.

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🛡️ How Projects Try to Prevent Sniping

Anti-bot Blacklists: Smart contracts block known wallets
Delayed Enable Trading: Add liquidity first, then enable trading 5 seconds later
Whitelist Windows: Only pre-approved wallets can trade at launch
Gas Limits: Revert trades with unusually high gas

Still, many snipers evolve faster than project defenses.

💬 Final Thoughts

Sniping bots expose the darker side of DeFi’s permissionless speed — where milliseconds and gas tricks can make or break a launch. While some view them as clever tools, others call them exploitative.

If you're a DeFi builder: consider snipe mitigation from day one. If you're a trader: beware the bots — you're not faster than code.