Uniswap

Swap Execution

• Slippage tolerance sets max acceptable price change — 0.5% for stablecoins, 1-3% for volatile pairs, higher for low liquidity tokens
• "Price impact" and "slippage" are different — impact is immediate effect of your trade size, slippage is protection against price movement
• High price impact (>2%) means you're moving the market — split large trades or use limit orders on Uniswap X
• Transaction deadline prevents stale swaps — 20-30 minutes default is usually fine, but pending tx beyond deadline will fail

MEV and Frontrunning

• Public swaps on Uniswap are visible in mempool before execution — bots can sandwich your trade
• Use MEV protection: swap through Uniswap wallet (built-in protection), or connect via Flashbots Protect RPC
• Signs of sandwich: execution price worse than quoted, with suspicious buy before and sell after your tx
• Uniswap X routes through private order flow — significantly reduces MEV extraction

Token Approval Traps

• First swap of any token requires approval transaction — this is normal, costs gas, and happens once per token per spender
• "Infinite approval" is the default — convenient but risky if Uniswap router is ever compromised
• Check and revoke old approvals at revoke.cash — approvals persist forever until explicitly revoked
• Approval transaction can succeed while swap fails — user pays gas for approval but swap reverts on slippage

Fake Tokens

• Anyone can create a token with any name and symbol — "USDC" on Uniswap might not be real USDC
• Always verify token contract address on CoinGecko, CoinMarketCap, or project's official site
• Warning signs: no liquidity, recently created, honeypot (can buy but not sell), tax on transfer
• Uniswap shows warning for unverified tokens — don't ignore it, especially for tokens you found via links

Liquidity Provision

• Impermanent loss is real and permanent when you withdraw — LPs lose vs just holding when prices diverge
• V3 concentrated liquidity amplifies both gains and losses — narrow range means more fees but higher IL risk
• Out-of-range positions earn zero fees — price moves outside your range, you hold 100% of the depreciating asset
• V2 is simpler: full range, less management, but less capital efficient — consider for volatile pairs you want to forget

V3 Position Management

• Narrower range = more fees per dollar but more rebalancing — only worth it if you actively manage
• Gas costs to adjust positions add up — each add/remove liquidity is a transaction
• "Collect fees" is separate from "remove liquidity" — uncollected fees stay in the position
• NFT represents your V3 position — losing the NFT means losing access to the liquidity

Gas Optimization

• Approve + swap is two transactions on first use — budget gas for both
• L2s (Arbitrum, Base, Optimism) have Uniswap with 10-50x lower fees — same interface, same liquidity depth
• Swapping during low gas periods (weekends, UTC night) saves significantly on mainnet
• Failed transactions still cost gas — simulate first if unsure about slippage or liquidity

Failed Swap Causes

• "Insufficient liquidity" — try smaller amount or different route
• "Slippage exceeded" — price moved during pending period, increase slippage or retry
• "Transfer failed" — token has transfer tax or restrictions, may be a scam token
• "Deadline exceeded" — transaction was pending too long, just retry
• "Approve first" — need to approve token before swap, this is normal

Uniswap X and Limit Orders

• Uniswap X uses off-chain orders filled by market makers — no gas if order isn't filled
• Limit orders let you set target price — order sits until price is reached or expires
• Partial fills possible — large orders may fill incrementally
• Check order status in the app — pending orders can be cancelled

Safety Checklist Before Large Swaps

• Verify token contract address matches official source
• Check price impact percentage — high impact means bad execution
• Confirm slippage is set appropriately for the pair
• Use MEV protection for mainnet trades
• Consider splitting very large trades
• Double-check recipient address if sending to different wallet