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

Class	Purpose
MarginfiClient	Main client for loading groups and banks
MarginfiAccountWrapper	User account management and lending operations
Bank	Individual lending pool configuration and state
Balance	Asset or liability position within an account
NodeWallet	Wallet adapter for server-side usage

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(borrowToken);
  
  if (!depositBank || !borrowBank) {
    throw new Error("Bank not found");
  }

  const signature = await account.repayWithCollateral(
    repayAmount,
    withdrawAmount,
    borrowBank.address,
    depositBank.address,
    swapInstructions,
    swapLookupTables
  );
  
  return signature;
}

Account Health

Computing Health Components

import { MarginRequirementType } from "@mrgnlabs/marginfi-client-v2";

// Get health components
const health = account.computeHealthComponents(MarginRequirementType.Initial);
console.log("Assets:", health.assets.toString());
console.log("Liabilities:", health.liabilities.toString());

// Get free collateral (borrowing capacity)
const freeCollateral = account.computeFreeCollateral();
console.log("Free collateral:", freeCollateral.toString());

Bank Information

Get Bank Details

const bank = client.getBankByTokenSymbol("SOL");
if (bank) {
  console.log("Address:", bank.address.toBase58());
  console.log("Token Symbol:", bank.tokenSymbol);
  console.log("Mint:", bank.mint.toBase58());
  console.log("Decimals:", bank.mintDecimals);
  
  // Compute rates
  const rates = bank.computeInterestRates();
  console.log("Lending Rate:", rates.lendingRate.toString());
  console.log("Borrowing Rate:", rates.borrowingRate.toString());
  
  // Compute totals
  const totalAssets = bank.getTotalAssetQuantity();
  const totalLiabilities = bank.getTotalLiabilityQuantity();
  const utilization = bank.computeUtilizationRate();
  
  console.log("Total Assets:", totalAssets.toString());
  console.log("Total Liabilities:", totalLiabilities.toString());
  console.log("Utilization:", utilization.toString());
}

Building Instructions (Low-Level)

For more control, build instructions separately:

// Build deposit instruction without executing
const { instructions, keys } = await account.makeDepositIx(
  1,
  solBank.address
);

// Build borrow instruction
const borrowIx = await account.makeBorrowIx(
  100,
  usdcBank.address
);

// Build repay instruction
const repayIx = await account.makeRepayIx(
  50,
  usdcBank.address
);

// Build withdraw instruction
const withdrawIx = await account.makeWithdrawIx(
  0.5,
  solBank.address
);

Environment Configuration

The SDK supports multiple environments:

import { getConfig } from "@mrgnlabs/marginfi-client-v2";

// Production (mainnet)
const prodConfig = getConfig("production");
// Program: MFv2hWf31Z9kbCa1snEPYctwafyhdvnV7FZnsebVacA
// Group: 4qp6Fx6tnZkY5Wropq9wUYgtFxXKwE6viZxFHg3rdAG8

// Alpha (mainnet)
const alphaConfig = getConfig("alpha");

// Staging
const stagingConfig = getConfig("staging");

// Development
const devConfig = getConfig("dev");

Constants

SDK exports useful constants:

import {
  PDA_BANK_LIQUIDITY_VAULT_AUTH_SEED,
  PDA_BANK_INSURANCE_VAULT_AUTH_SEED,
  PDA_BANK_FEE_VAULT_AUTH_SEED,
  PYTH_PRICE_CONF_INTERVALS,
  SWB_PRICE_CONF_INTERVALS,
  MAX_CONFIDENCE_INTERVAL_RATIO,
  DEFAULT_ORACLE_MAX_AGE,
  USDC_DECIMALS,
  ADDRESS_LOOKUP_TABLE_FOR_GROUP,
} from "@mrgnlabs/marginfi-client-v2";

Resources

Resource	Link
Official SDK Documentation	docs.marginfi.com/ts-sdk
Protocol Documentation	docs.marginfi.com
GitHub Repository	github.com/mrgnlabs/mrgn-ts
SDK Package	@mrgnlabs/marginfi-client-v2
Common utilities	@mrgnlabs/mrgn-common
SDK Configs	configs.json (repo)
SDK Constants	constants.ts (repo)

Note: The linked configs.json and constants.ts may not be exhaustive — check the official repository for the latest values and additional constants.

Related Files

• marginfi-sdk-api-reference.md - Complete API reference
• program-addresses.md - Program and account addresses
• troubleshooting.md - Common issues and solutions