1 Best APIs for Bank Account Linking (Connect Widget) in Nigeria

Mono is a Nigerian open banking and financial data infrastructure company that enables developers to build financial products by connecting customer bank accounts for data access, payments, and identity verification. Founded in 2020 by Abdul Hassan and Prakhar Sharma, Mono has raised funding from Sequoia Capital India and other top investors, and is one of Africa's leading open banking providers, covering over 30 Nigerian banks and financial institutions. The Mono platform is organized into three main API products: Financial Data, Payments (DirectPay), and Identity Verification. All three use the same developer credentials and are accessed via the Mono Connect widget — an embeddable authentication flow that allows customers to authorize Mono's access to their bank account using their internet banking credentials, in accordance with CBN open banking guidelines. The Financial Data API provides programmatic access to a bank account's transaction history, current balance, income patterns, and bank statements after the customer authorizes access through the Connect widget. Lenders use this data for credit scoring — analyzing spending patterns, income credits, and debt obligations from actual bank statements rather than relying on self-reported income. The transactions endpoint returns categorized transaction records covering 12–24 months of history depending on the bank. The Payments API, branded as DirectPay, enables businesses to initiate single direct debits from a linked customer bank account — charging the account directly without requiring the customer to enter card details. DirectPay is powered by open banking standards, with all transactions encrypted end-to-end. Pricing is 1% per successful transaction, capped at NGN 1,000. This makes DirectPay significantly cheaper than card payment fees (Paystack charges 1.5% + ₦100 capped at ₦2,000) for high-value transactions — for example, a ₦500,000 loan repayment via DirectPay costs ₦1,000 (capped), versus ₦2,100 via card. Mono also offers a Recurring Direct Debit product — where a customer authorizes ongoing debits on a schedule — enabling subscription billing, loan installment plans, and salary deductions using open banking mandates rather than card tokens. Authentication is handled via the Client Secret Key, which is included in request headers as mono-sec-key. Public keys are used client-side to initialize the Connect widget. Mono provides SDKs for React, React Native, JavaScript, Android, and iOS — all of which embed the Connect widget and handle the token exchange flow. Most integrations take 2–4 hours. For identity verification, Mono offers BVN verification, NIN verification, and document verification (government-issued ID). These are standalone API calls that do not require bank account linking — useful for KYC onboarding where the business needs to verify user identity before granting access to financial services. Mono's Identity API also supports address verification and company verification via CAC data — enabling Know Your Business (KYB) checks for B2B platforms and marketplace operators. The sandbox environment is available at mono.co/sandbox with test bank credentials provided in the documentation. All three products (Financial Data, DirectPay, Identity Verification) are testable in sandbox mode before going live. From a compliance standpoint, Mono operates under the CBN's Regulatory Framework for Open Banking in Nigeria. All data access is customer-authorized and consent-revocable. Mono is registered with the Nigerian Data Protection Regulation (NDPR) as a data controller and processor. The Connect widget displays clearly what data a business is requesting before the customer approves access. Mono covers over 30 Nigerian financial institutions including GTBank, First Bank, Zenith Bank, Access Bank, UBA, Sterling Bank, Kuda, OPay, PalmPay, and most major microfinance banks. Frequently Asked Questions: Can I access a customer's bank account without their permission? No — the Mono Connect widget requires explicit customer authorization. The customer sees exactly what data the platform is requesting and must provide their internet banking credentials to approve access. How long does bank account access last? Customer authorizations can expire or be revoked. Mono's refresh token mechanism allows businesses to refresh data access periodically, but customers can revoke access at any time via the Mono Customer Portal. Does DirectPay work for all Nigerian banks? DirectPay covers 30+ institutions but not all banks. Coverage continues to expand as Mono adds new integrations. Can I use Mono for business account verification? Yes — Mono's Identity API includes CAC verification for business account checks, in addition to individual BVN/NIN verification.