TrueLayer API Integration for Secure Open Banking Apps

TrueLayer API: Complete Developer Guide for Open Banking in the USA

What Is the TrueLayer API?

The TrueLayer API is an open banking platform that gives developers secure, real-time access to bank account data, instant payment initiation, and identity verification — all through a single, unified API connection. TrueLayer provides real-time bank payments, data, and identity APIs, helping businesses of all sizes accept and send instant payments via open banking rails. 

For US-based fintech developers and financial institutions, integrating the TrueLayer API means faster onboarding, lower fraud risk, and cleaner payment flows — without the complexity of connecting directly to dozens of individual bank APIs.

How the TrueLayer API Works

Some TPPs, including TrueLayer, specialize in aggregating bank APIs and can make all banks available to businesses through a single API connection TrueLayer, removing the need to manage individual bank integrations yourself. Here's the core flow:

Data API Flow (Account Connectivity):

1. User clicks "Connect Bank" inside your app

2. TrueLayer presents a bank selection screen

3. User authenticates via OAuth redirect to their bank

4. TrueLayer retrieves authorized data (balances, transactions, identity)

5. Your app receives clean, standardized JSON responses

Payments API Flow (Pay by Bank):

1. User selects "Pay by Bank" at checkout

2. TrueLayer initiates a secure payment request

3. User is redirected to their banking app

4. User approves via biometrics or PIN

5. Funds transfer instantly — no card details involved

TrueLayer API: Core Products at a Glance

TrueLayer API: Key Features for US Fintech Developers

Financial Data Access The Data API allows you to access account holder name, account number, IBAN, credit card details, transactions with description and merchant name, current and available balances, and regular payments like standing orders and direct debits.

Instant Payments (Pay by Bank) Pay by Bank means customers simply pay directly from their bank account via their bank app. It takes the friction out of your checkout, and sees returning customers converting at up to 90%.

Security & Compliance TrueLayer is fully regulated, authorized by the UK Financial Conduct Authority (FCA) as both an AISP and PISP, and PSD2 compliant with passporting rights across the EU. UBS All API responses use OAuth 2.0, end-to-end encryption, and TLS in transit.

Developer-Ready Tooling All responses returned by TrueLayer APIs are in JSON format. TrueLayer TrueLayer also provides SDKs for iOS, Android, and React Native, plus a sandbox environment for safe testing before going live.

Technical Integration: TrueLayer API Code Examples

1. Authentication — Get an Access Token

// Exchange auth code for access token
const response = await fetch('https://auth.truelayer.com/connect/token', {
  method: 'POST',
  headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
  body: new URLSearchParams({
    grant_type: 'authorization_code',
    client_id: 'YOUR_CLIENT_ID',
    client_secret: 'YOUR_CLIENT_SECRET',
    redirect_uri: 'https://yourapp.com/callback',
    code: 'AUTH_CODE_FROM_REDIRECT'
  })
});

const { access_token } = await response.json();

2. Fetch Account Balances

// Get real-time account balance
const balanceRes = await fetch(
  'https://api.truelayer.com/data/v1/accounts/{accountId}/balance',
  {
    headers: {
      Authorization: `Bearer ${access_token}`
    }
  }
);

const balanceData = await balanceRes.json();
// Response: { current: 2450.00, available: 2100.00, currency: "GBP" }

3. Fetch Transactions

// Retrieve transaction history
const txRes = await fetch(
  'https://api.truelayer.com/data/v1/accounts/{accountId}/transactions',
  {
    headers: { Authorization: `Bearer ${access_token}` }
  }
);

const { results } = await txRes.json();
// Each result: { amount, description, category, merchant_name, timestamp }

4. Initiate a Payment (Payments API v3)

// Create an instant bank payment
const paymentRes = await fetch('https://payment.truelayer.com/payments', {
  method: 'POST',
  headers: {
    Authorization: `Bearer ${access_token}`,
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    amount_in_minor: 5000,       // £50.00 in pence
    currency: 'GBP',
    payment_method: {
      type: 'bank_transfer',
      provider_selection: { type: 'user_selected' },
      beneficiary: {
        type: 'merchant_account',
        merchant_account_id: 'YOUR_MERCHANT_ACCOUNT_ID'
      }
    },
    user: {
      id: 'user-001',
      name: 'Jane Smith',
      email: 'jane@example.com'
    }
  })
});

const { id, resource_token } = await paymentRes.json();
// Use resource_token to redirect user to the TrueLayer payment UI

TrueLayer API Capabilities Comparison

Use Cases: What US Fintech Teams Build With TrueLayer API

Personal Finance Apps — Aggregate account balances and transactions from multiple banks into a single dashboard, giving users a unified view of their financial health.

Lending & Credit Platforms — Use real-time transaction data for affordability assessments and income verification during loan onboarding, cutting approval times dramatically.

Payment Gateways — Replace expensive card-based checkout flows with direct bank-to-bank payments that carry lower processing fees and zero card fraud exposure.

KYC & Onboarding Flows — The Data API provides a seamless and safe way to verify account ownership and transaction history, helping onboard new customers quickly while they are most engaged. TrueLayer

Wealth Management Tools — Connect investment, savings, and bank accounts to give clients a complete financial picture alongside portfolio data.

Why FintegrationFS Uses TrueLayer API for US Fintech Builds

At FintegrationFS, we integrate the TrueLayer API as part of broader mobile banking app development and fintech platform builds for US clients. When your product needs reliable financial data, instant payment rails, or compliant identity verification, TrueLayer is one of the production-ready tools we reach for — especially for teams that need to move fast without compromising on data integrity or security.

Our team handles the full integration lifecycle: sandbox setup, OAuth flows, webhook handling, error states, and reconciliation logic — so your engineering team can stay focused on your core product.

FAQ 

Q1: Is TrueLayer API available for US-based companies? 

Yes. While TrueLayer's direct bank network is strongest in the UK and Europe, US-based fintech companies and developers can access TrueLayer's APIs and build products using its infrastructure. Many US fintechs partner with implementation firms like FintegrationFS to integrate TrueLayer as part of a broader open banking or payment stack.

Q2: What is the TrueLayer API used for?

The TrueLayer API is primarily used for three things: accessing real-time bank account data (balances, transactions, identity), initiating instant bank-to-bank payments, and verifying user identity against their bank records. It's commonly used in lending, personal finance, payments, and KYC-heavy onboarding flows.

Q3: How does TrueLayer API authentication work? 

TrueLayer uses OAuth 2.0, which gives consumers and businesses the right to access their account data and payments through authorized third-party providers. TrueLayer Users authenticate directly with their bank, and TrueLayer issues access tokens your application uses to retrieve data or initiate payments.

Q4: What data can I access through the TrueLayer Data API? 

You can access account holder name, account number, IBAN, transaction description and category, merchant names, current and available balances, and regular payments like standing orders and direct debits. TrueLayer

Q5: Is TrueLayer API secure and compliant? 

Yes. TrueLayer is guided by regulatory compliance and user consent Open Banking, uses end-to-end encryption, OAuth 2.0 for authentication, and is authorized as both an Account Information Service Provider (AISP) and Payment Initiation Service Provider (PISP).

Q6: What is the latest version of the TrueLayer Payments API? 

The Payments API v3 is the latest version, supporting more functionality than older versions, including closed loop and open loop payments, payouts, refunds, and variable recurring payments. TrueLayer

Q7: How long does it take to integrate the TrueLayer API? 

A basic sandbox integration can be set up in a matter of days. A production-ready integration with full error handling, webhook retries, and reconciliation logic typically takes 2–4 weeks depending on your stack and use case. Working with an experienced fintech development partner like FintegrationFS can significantly reduce that timeline.

Q8: What is "Pay by Bank" powered by TrueLayer? 

Pay by Bank is an open banking payment that allows a customer to pay for something online straight from their bank account — whether buying from an online store or topping up a wealth management app. TrueLayer It removes card friction, lowers fees for merchants, and eliminates card fraud risk entirely.