kimi-dex

A minimal Uniswap V2-style AMM DEX for Monad, built with Foundry.

Architecture

Contract	Purpose
src/DexFactory.sol	Deploys and indexes one DexPair per token pair (CREATE2). Holds the optional protocol-fee switch (feeTo).
src/DexPair.sol	Constant-product (x * y = k) pool for two ERC-20 tokens. The pair contract is itself the ERC-20 LP token. Swaps charge a 0.30% fee that accrues to LPs; TWAP price accumulators included.
src/DexRouter.sol	Stateless entry point: addLiquidity, removeLiquidity, swapExactTokensForTokens, swapTokensForExactTokens (multi-hop supported), plus quote helpers.
src/WMON.sol	Wrapped MON (WETH9-style). Wrap native MON to trade it on the DEX.
src/mocks/MockERC20.sol	Mintable ERC-20 for tests and testnet demos.

Trading works exactly like Uniswap V2: LPs deposit both sides of a pair and receive LP tokens; swappers trade against the pool's reserves and pay 0.30%, which stays in the pool. If feeTo is set on the factory, 1/6 of the fee growth is minted to that address as the protocol fee.

Networks

	Chain ID	RPC	Explorer
Monad Testnet	10143	https://testnet-rpc.monad.xyz	https://testnet.monadvision.com
Monad Mainnet	143	https://rpc.monad.xyz	https://monadvision.com

Both are preconfigured as monad_testnet / monad_mainnet in foundry.toml.

Live deployment (Monad Testnet)

Deployed and verified on both Monadscan and MonadVision:

Contract	Address
WMON	0xBeC7f7D06b75b6cbDE340440B6419C23b3C9bc67
DexFactory	0x8dae2b96dE2DAbDa5a1Ad1ed6157046D9019083b
DexRouter	0xdf5F0C7e6f3b9BCF4d2B34909F3eC78F2D398a72
Demo pair (KTA/KTB)	0x7992A6F8b39d77D2C54dc4849f73d72a428dB61D

Demo tokens: KTA 0xe9b877a4E4ebe261a716ECAe16aDa95bd1F6cB09, KTB 0x30050f6e132B028B9185122334fdB462e9B35C39 (both MockERC20 with public mint).

Build & test

forge build
forge test

Deploy

1. Get testnet MON from the faucet.
2. cp .env.example .env and fill in PRIVATE_KEY (or use a keystore instead).
3. Deploy:

source .env
forge script script/Deploy.s.sol --rpc-url monad_testnet --broadcast

The script deploys WMON, DexFactory, and DexRouter and prints their addresses. For mainnet, swap in --rpc-url monad_mainnet.

Use it (cast examples)

Set the deployed addresses:

export FACTORY=0x... ROUTER=0x... WMON=0x...

Deploy two demo tokens and mint yourself some supply:

export TKA=$(forge create src/mocks/MockERC20.sol:MockERC20 --rpc-url monad_testnet --private-key $PRIVATE_KEY --broadcast --constructor-args "Token A" TKA | awk '/Deployed to:/ {print $3}')
export TKB=$(forge create src/mocks/MockERC20.sol:MockERC20 --rpc-url monad_testnet --private-key $PRIVATE_KEY --broadcast --constructor-args "Token B" TKB | awk '/Deployed to:/ {print $3}')
cast send $TKA "mint(address,uint256)" $YOUR_ADDRESS 1000000ether --rpc-url monad_testnet --private-key $PRIVATE_KEY
cast send $TKB "mint(address,uint256)" $YOUR_ADDRESS 1000000ether --rpc-url monad_testnet --private-key $PRIVATE_KEY

Add liquidity (creates the pair automatically):

cast send $TKA "approve(address,uint256)" $ROUTER 10000ether --rpc-url monad_testnet --private-key $PRIVATE_KEY
cast send $TKB "approve(address,uint256)" $ROUTER 10000ether --rpc-url monad_testnet --private-key $PRIVATE_KEY
cast send $ROUTER "addLiquidity(address,address,uint256,uint256,uint256,uint256,address,uint256)" \
  $TKA $TKB 1000ether 4000ether 0 0 $YOUR_ADDRESS $(($(date +%s) + 600)) \
  --rpc-url monad_testnet --private-key $PRIVATE_KEY

Swap 1 TKA for TKB:

cast send $ROUTER "swapExactTokensForTokens(uint256,uint256,address[],address,uint256)" \
  1ether 0 "[$TKA,$TKB]" $YOUR_ADDRESS $(($(date +%s) + 600)) \
  --rpc-url monad_testnet --private-key $PRIVATE_KEY

Quote a swap without sending it:

cast call $ROUTER "getAmountsOut(uint256,address[])(uint256[])" 1ether "[$TKA,$TKB]" --rpc-url monad_testnet

Wrap/unwrap native MON:

cast send $WMON "deposit()" --value 10ether --rpc-url monad_testnet --private-key $PRIVATE_KEY
cast send $WMON "withdraw(uint256)" 10ether --rpc-url monad_testnet --private-key $PRIVATE_KEY

Frontend

A Next.js + wagmi/RainbowKit UI for the DEX lives in web/ — swap, add/remove liquidity, and mint demo tokens (KTA/KTB) against the live testnet deployment above.

Live at https://kimi-dex.vercel.app

Run locally:

cd web
npm install
npm run dev

Notes

• The router is token-to-token only; wrap MON into WMON first to trade it.
• Solidity 0.8.28, evm_version = cancun.
• Not audited. For learning and testnet use.