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Code examples for common swap scenarios using the Stableswapper program on Solana devnet.
These examples assume you’ve completed the Quickstart setup steps (dependencies, environment variables, and IDL).

​
Setup

Use these devnet addresses in your examples. For mainnet, replace with your production addresses from Key Addresses. 
import * as anchor from "@coral-xyz/anchor";
import { Program, AnchorProvider } from "@coral-xyz/anchor";
import { PublicKey } from "@solana/web3.js";
import {
  TOKEN_PROGRAM_ID,
  ASSOCIATED_TOKEN_PROGRAM_ID,
  getAssociatedTokenAddress,
  getAccount,
  createAssociatedTokenAccountInstruction,
} from "@solana/spl-token";
import idl from "./custom_stablecoins.json";

// Devnet addresses
const PROGRAM_ID        = new PublicKey("9vDwZVJXw5nxymWmUcgmNpemDH5EBcJwLNhtsznrgJDH");
const USDC_MINT         = new PublicKey("4zMMC9srt5Ri5X14GAgXhaHii3GnPAEERYPJgZJDncDU");
const CUSTOM_TOKEN_MINT = new PublicKey("AreQsswF44khJHLjsuWzgboJcG31JvALcWMkMcsVs2uC"); // SFTUSD25

const provider = anchor.AnchorProvider.env();
anchor.setProvider(provider);
// @ts-ignore - IDL type compatibility
const program = new Program(idl, provider);

​
Swap USDC for custom token

async function swapUsdcForCustomToken() {
  const swapAmount   = new anchor.BN(0.1 * 10 ** 6);   // 0.1 USDC (6 decimals)
  const minAmountOut = new anchor.BN(0.09 * 10 ** 6);  // Allow up to 10% for fees/slippage

  // Derive PDAs
  const [pool] = PublicKey.findProgramAddressSync(
    [Buffer.from("liquidity_pool")],
    PROGRAM_ID
  );

  const [usdcVault] = PublicKey.findProgramAddressSync(
    [Buffer.from("token_vault"), pool.toBuffer(), USDC_MINT.toBuffer()],
    PROGRAM_ID
  );

  const [customTokenVault] = PublicKey.findProgramAddressSync(
    [Buffer.from("token_vault"), pool.toBuffer(), CUSTOM_TOKEN_MINT.toBuffer()],
    PROGRAM_ID
  );

  const [usdcVaultTokenAccount] = PublicKey.findProgramAddressSync(
    [Buffer.from("vault_token_account"), usdcVault.toBuffer()],
    PROGRAM_ID
  );

  const [customTokenVaultTokenAccount] = PublicKey.findProgramAddressSync(
    [Buffer.from("vault_token_account"), customTokenVault.toBuffer()],
    PROGRAM_ID
  );

  const [whitelist] = PublicKey.findProgramAddressSync(
    [Buffer.from("address_whitelist")],
    PROGRAM_ID
  );

  // User token accounts
  const userUsdcAccount = await getAssociatedTokenAddress(
    USDC_MINT,
    provider.wallet.publicKey
  );

  const userCustomTokenAccount = await getAssociatedTokenAddress(
    CUSTOM_TOKEN_MINT,
    provider.wallet.publicKey
  );

  // Fetch pool to get fee recipient
  const poolAccount = await (program.account as any).liquidityPool.fetch(pool);

  const feeRecipientUsdcAccount = await getAssociatedTokenAddress(
    USDC_MINT,
    poolAccount.feeRecipient
  );

  // Create destination ATA if it doesn't exist
  let needsAccountCreation = false;
  try {
    await getAccount(provider.connection, userCustomTokenAccount);
  } catch {
    needsAccountCreation = true;
  }

  // Build swap instruction
  const swapIx = await program.methods
    .swap(swapAmount, minAmountOut)
    .accounts({
      pool,
      inVault: usdcVault,
      outVault: customTokenVault,
      inVaultTokenAccount: usdcVaultTokenAccount,
      outVaultTokenAccount: customTokenVaultTokenAccount,
      userFromTokenAccount: userUsdcAccount,
      toTokenAccount: userCustomTokenAccount,
      feeRecipientTokenAccount: feeRecipientUsdcAccount,
      feeRecipient: poolAccount.feeRecipient,
      fromMint: USDC_MINT,
      toMint: CUSTOM_TOKEN_MINT,
      user: provider.wallet.publicKey,
      whitelist,
      tokenProgram: TOKEN_PROGRAM_ID,
      associatedTokenProgram: ASSOCIATED_TOKEN_PROGRAM_ID,
      systemProgram: anchor.web3.SystemProgram.programId,
    } as any)
    .instruction();

  // Optionally prepend ATA creation
  const transaction = new anchor.web3.Transaction();
  if (needsAccountCreation) {
    transaction.add(
      createAssociatedTokenAccountInstruction(
        provider.wallet.publicKey,
        userCustomTokenAccount,
        provider.wallet.publicKey,
        CUSTOM_TOKEN_MINT
      )
    );
  }
  transaction.add(swapIx);

  const tx = await provider.sendAndConfirm(transaction);
  console.log("Swap successful:", tx);
}

​
Swap custom token for USDC

async function swapCustomTokenForUsdc() {
  const swapAmount   = new anchor.BN(0.1 * 10 ** 6);   // 0.1 custom tokens (6 decimals)
  const minAmountOut = new anchor.BN(0.09 * 10 ** 6);  // Allow up to 10% for fees/slippage

  // Derive PDAs
  const [pool] = PublicKey.findProgramAddressSync(
    [Buffer.from("liquidity_pool")],
    PROGRAM_ID
  );

  const [customTokenVault] = PublicKey.findProgramAddressSync(
    [Buffer.from("token_vault"), pool.toBuffer(), CUSTOM_TOKEN_MINT.toBuffer()],
    PROGRAM_ID
  );

  const [usdcVault] = PublicKey.findProgramAddressSync(
    [Buffer.from("token_vault"), pool.toBuffer(), USDC_MINT.toBuffer()],
    PROGRAM_ID
  );

  const [customTokenVaultTokenAccount] = PublicKey.findProgramAddressSync(
    [Buffer.from("vault_token_account"), customTokenVault.toBuffer()],
    PROGRAM_ID
  );

  const [usdcVaultTokenAccount] = PublicKey.findProgramAddressSync(
    [Buffer.from("vault_token_account"), usdcVault.toBuffer()],
    PROGRAM_ID
  );

  const [whitelist] = PublicKey.findProgramAddressSync(
    [Buffer.from("address_whitelist")],
    PROGRAM_ID
  );

  // User token accounts
  const userCustomTokenAccount = await getAssociatedTokenAddress(
    CUSTOM_TOKEN_MINT,
    provider.wallet.publicKey
  );

  const userUsdcAccount = await getAssociatedTokenAddress(
    USDC_MINT,
    provider.wallet.publicKey
  );

  // Fetch pool to get fee recipient
  const poolAccount = await (program.account as any).liquidityPool.fetch(pool);

  const feeRecipientCustomTokenAccount = await getAssociatedTokenAddress(
    CUSTOM_TOKEN_MINT,
    poolAccount.feeRecipient
  );

  // Build and send swap
  const swapIx = await program.methods
    .swap(swapAmount, minAmountOut)
    .accounts({
      pool,
      inVault: customTokenVault,
      outVault: usdcVault,
      inVaultTokenAccount: customTokenVaultTokenAccount,
      outVaultTokenAccount: usdcVaultTokenAccount,
      userFromTokenAccount: userCustomTokenAccount,
      toTokenAccount: userUsdcAccount,
      feeRecipientTokenAccount: feeRecipientCustomTokenAccount,
      feeRecipient: poolAccount.feeRecipient,
      fromMint: CUSTOM_TOKEN_MINT,
      toMint: USDC_MINT,
      user: provider.wallet.publicKey,
      whitelist,
      tokenProgram: TOKEN_PROGRAM_ID,
      associatedTokenProgram: ASSOCIATED_TOKEN_PROGRAM_ID,
      systemProgram: anchor.web3.SystemProgram.programId,
    } as any)
    .instruction();

  const transaction = new anchor.web3.Transaction();
  transaction.add(swapIx);

  const tx = await provider.sendAndConfirm(transaction);
  console.log("Swap successful:", tx);
}

​
Swap between two custom stablecoins

The program supports swapping between any two supported tokens — not just USDC pairs. To swap between two custom stablecoins, substitute both CUSTOM_TOKEN_MINT references with the respective fromMint and toMint addresses for your tokens.

Reference

Complete swap instruction parameters and accounts

Production Readiness

Helper functions and best practices

Quickstart

Get up and running in 10 minutes

Key Addresses

Program IDs and deployed addresses