Marginfi Development Guide

Build lending and borrowing applications on Solana with Marginfi - a decentralized, overcollateralized lending protocol offering deposits, borrows, flash loans, and leveraged positions.

Overview

Marginfi provides:

• Lending & Borrowing: Deposit collateral to earn yield, borrow against your deposits
• Multiple Accounts: Create multiple accounts per wallet with independent positions
• Risk Management: Advanced health calculations using asset and liability weights
• Flash Loans: Atomic, uncollateralized lending within a single transaction
• Looping: Leverage positions by depositing and borrowing in a single transaction
• Multi-Asset Support: SOL, USDC, LSTs (JitoSOL, mSOL), and more

Quick Start

Installation

# Marginfi client SDK
npm install @mrgnlabs/marginfi-client-v2

# Common utilities
npm install @mrgnlabs/mrgn-common

# Required peer dependencies
npm install @solana/web3.js @coral-xyz/anchor

Environment Setup

# .env file
SOLANA_RPC_URL=https://api.mainnet-beta.solana.com
WALLET_KEYPAIR_PATH=./keypair.json

Marginfi SDK (marginfi-client-v2)

The SDK enables interaction with Marginfi's lending protocol for deposits, borrows, repayments, withdrawals, and advanced operations.

Core Classes

Initialize Client

import { MarginfiClient, getConfig } from "@mrgnlabs/marginfi-client-v2";
import { NodeWallet } from "@mrgnlabs/mrgn-common";
import { Connection, Keypair } from "@solana/web3.js";

const connection = new Connection("https://api.mainnet-beta.solana.com");
const keypair = Keypair.fromSecretKey(/* your secret key */);
const wallet = new NodeWallet(keypair);

// Get production configuration
const config = getConfig("production");

// Load Marginfi client
const client = await MarginfiClient.fetch(config, wallet, connection);

// Access banks
for (const [address, bank] of client.banks) {
  console.log(`${bank.tokenSymbol}: ${address}`);
}

Get Bank by Token

// Get bank by token symbol
const solBank = client.getBankByTokenSymbol("SOL");
const usdcBank = client.getBankByTokenSymbol("USDC");

// Get bank by mint address
const usdcMint = new PublicKey("EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v");
const usdcBankByMint = client.getBankByMint(usdcMint);

// Get bank by public key
const bank = client.getBankByPk(new PublicKey("..."));

Create Account

// Create a new Marginfi account
const account = await client.createMarginfiAccount();

console.log("Account address:", account.address.toBase58());
console.log("Authority:", account.authority.toBase58());

Fetch Existing Accounts

// Get all accounts for a wallet
const accounts = await client.getMarginfiAccountsForAuthority(wallet.publicKey);

for (const account of accounts) {
  console.log("Account:", account.address.toBase58());
  console.log("Active balances:", account.activeBalances.length);
  
  // Check positions
  for (const balance of account.activeBalances) {
    const bank = client.getBankByPk(balance.bankPk);
    const quantity = balance.computeQuantityUi(bank!);
    console.log(`  ${bank?.tokenSymbol}: Assets=${quantity.assets}, Liabilities=${quantity.liabilities}`);
  }
}

Deposit Collateral

async function deposit(
  account: MarginfiAccountWrapper,
  client: MarginfiClient,
  tokenSymbol: string,
  amount: number // UI-denominated amount (tokens, e.g., 1 for 1 SOL)
) {
  const bank = client.getBankByTokenSymbol(tokenSymbol);
  if (!bank) throw new Error(`Bank ${tokenSymbol} not found`);

  // Execute deposit
  const signature = await account.deposit(amount, bank.address);
  
  console.log("Deposit signature:", signature);
  return signature;
}

// Example: Deposit 1 SOL
await deposit(account, client, "SOL", 1);

Borrow Assets

async function borrow(
  account: MarginfiAccountWrapper,
  client: MarginfiClient,
  tokenSymbol: string,
  amount: number
) {
  const bank = client.getBankByTokenSymbol(tokenSymbol);
  if (!bank) throw new Error(`Bank ${tokenSymbol} not found`);

  // Execute borrow
    const signature = await account.borrow(amount, bank.address);
  
  console.log("Borrow signature:", signature);
  return signature;
}

// Example: Borrow 100 USDC
await borrow(account, client, "USDC", 100);

Repay Debt

async function repay(
  account: MarginfiAccountWrapper,
  client: MarginfiClient,
  tokenSymbol: string,
  amount: number,
  repayAll: boolean = false
) {
  const bank = client.getBankByTokenSymbol(tokenSymbol);
  if (!bank) throw new Error(`Bank ${tokenSymbol} not found`);

  // Execute repay
  const signature = await account.repay(amount, bank.address, repayAll);
  
  console.log("Repay signature:", signature);
  return signature;
}

// Partial repay
await repay(account, client, "USDC", 50);

// Repay all (handles accrued interest)
await repay(account, client, "USDC", 0, true);

Withdraw Collateral

async function withdraw(
  account: MarginfiAccountWrapper,
  client: MarginfiClient,
  tokenSymbol: string,
  amount: number,
  withdrawAll: boolean = false
) {
  const bank = client.getBankByTokenSymbol(tokenSymbol);
  if (!bank) throw new Error(`Bank ${tokenSymbol} not found`);

  // Execute withdraw
  const signature = await account.withdraw(amount, bank.address, withdrawAll);
  
  console.log("Withdraw signature:", signature);
  return signature;
}

// Partial withdraw
await withdraw(account, client, "SOL", 0.5);

// Withdraw all
await withdraw(account, client, "SOL", 0, true);

Advanced Operations

Flash Loans

Execute uncollateralized loans that must be repaid within the same transaction:

import { TransactionInstruction } from "@solana/web3.js";

async function executeFlashLoan(
  account: MarginfiAccountWrapper,
  customInstructions: TransactionInstruction[]
) {
  // Flash loan allows you to borrow without collateral
  // as long as you repay in the same transaction
  const signature = await account.flashLoan({
    ixs: customInstructions
  });
  
  console.log("Flash loan signature:", signature);
  return signature;
}

Looping (Leverage)

Deposit and borrow in a single transaction for leveraged positions:

import { AddressLookupTableAccount, TransactionInstruction } from "@solana/web3.js";

async function loop(
  account: MarginfiAccountWrapper,
  client: MarginfiClient,
  depositToken: string,
  borrowToken: string,
  depositAmount: number,
  borrowAmount: number,
  swapInstructions: TransactionInstruction[],
  swapLookupTables: AddressLookupTableAccount[]
) {
  const depositBank = client.getBankByTokenSymbol(depositToken);
  const borrowBank = client.getBankByTokenSymbol(borrowToken);
  
  if (!depositBank || !borrowBank) {
    throw new Error("Bank not found");
  }

  const signature = await account.loop(
    depositAmount,
    borrowAmount,
    depositBank.address,
    borrowBank.address,
    swapInstructions,
    swapLookupTables
  );
  
  console.log("Loop signature:", signature);
  return signature;
}

Repay with Collateral

Repay debt using deposited collateral via a swap:

async function repayWithCollateral(
  account: MarginfiAccountWrapper,
  client: MarginfiClient,
  repayAmount: number,
  withdrawAmount: number,
  depositToken: string,
  borrowToken: string,
  swapInstructions: TransactionInstruction[],
  swapLookupTables: AddressLookupTableAccount[]
) {
  const depositBank = client.getBankByTokenSymbol(depositToken);
  const borrowBank = client.getBankByTokenSymbol(bor