stableswappy

Python package for Stableswap V1 modelling

🔗 SPDX-Anchor: anchorregistry.ai/AR-2026-PZYDyE1

Install

To install package:

> git clone https://github.com/defipy-devs/stableswappy
> pip install .

or

> pip install StableswapPy

Stableswap

• See test notebook for basic usage

from stableswappy import *

user_nm = 'user_test'

user_nm = 'user_test'

AMPL_COEFF = 2000 

amt_dai = 79566307.559825807715868071
decimal_dai = 18

amt_usdc = 81345068.187939
decimal_usdc = 6

amt_usdt = 55663250.772939
decimal_usdt = 6

dai = ERC20("DAI", "0xA0b", decimal_dai)
dai.deposit(None, amt_dai)

usdc = ERC20("USDC", "0xf93", decimal_usdc)
usdc.deposit(None, amt_usdc)

usdt = ERC20("USDT", "0xd7c", decimal_usdt)
usdt.deposit(None, amt_usdt)

sgrp = StableswapVault()
sgrp.add_token(dai)
sgrp.add_token(usdc)
sgrp.add_token(usdt)

sfactory = StableswapFactory("Pool factory", "0x2")
exchg_data = StableswapExchangeData(vault = sgrp, symbol="LP", address="0x011")
lp = sfactory.deploy(exchg_data)

Join().apply(lp, user_nm, AMPL_COEFF)
lp.summary()

OUTPUT:

Stableswap Exchange: DAI-USDC-USDT (LP)
Reserves: DAI = 79566307.55982581, USDC = 81345068.187939, USDT = 55663250.772939
Liquidity: 216573027.91811988

Swap

usdc_before = lp.get_reserve(usdc)
usdt_before = lp.get_reserve(usdt)

amt_tkn_in = 10000
tkn_in = usdc
tkn_out = usdt
res = Swap().apply(lp, tkn_in, tkn_out, user_nm, amt_tkn_in)
lp.summary()

print(f"{amt_tkn_in} {tkn_in.token_name} was swapped for {res['tkn_out_amt']} {tkn_out.token_name}")

OUTPUT:

Stableswap Exchange: DAI-USDC-USDT (LP)
Reserves: DAI = 79566307.55982581, USDC = 81355068.187939, USDT = 55653253.910191
Liquidity: 216573027.91811988

10000 USDC was swapped for 9996.862748 USDT

Swap

usdc_before = lp.get_reserve(usdc)
dai_before = lp.get_reserve(dai)

amt_tkn_in = 10000
tkn_in = usdc
tkn_out = dai
res = Swap().apply(lp, tkn_in, tkn_out, user_nm, amt_tkn_in)
lp.summary()

print(f"{amt_tkn_in} {tkn_in.token_name} was swapped for {res['tkn_out_amt']} {tkn_out.token_name}")

Stableswap Exchange: DAI-USDC-USDT (LP)
Reserves: DAI = 79556308.6645169, USDC = 81365068.187939, USDT = 55653253.910191
Liquidity: 216573027.91811988

10000 USDC was swapped for 9998.895308918858 DAI

Testing

Run the full test suite from the repo root:

> python -m pytest python/test/ -v

Tests cover:

• Process: join, swap (near-peg slippage, fee verification, reserve changes), add/remove liquidity
• Math: D invariant stability, exchange output, virtual price, spot price (dydx), and calc_token_amount

Requirements

> pip install pytest gmpy2

License

Licensed under the Apache License, Version 2.0.
See LICENSE and NOTICE for details.
Portions of this project may include code from third-party projects under compatible open-source licenses.