Decimal Finance Case Study Hero Background

How Decimal Finance Launched a Secure UPI Payments App Supporting 4-Bank Integration and Real-Time Transfers

LocationIndia

SolutionUPI Payments Mobile App

Banks Integrated at Launch

<2 sec

Average Transfer Completion Time

Unified Financial Dashboard

At-a-Glance

Decimal Finance, an Indian fintech startup entering the UPI digital payments space

Case Study

CHALLENGE:

Building a NPCI-compliant UPI application that supports multiple bank accounts simultaneously while delivering a consumer-grade UX in a competitive market

SOLUTION:

Intelegain engineered a secure, multi-bank UPI app with real-time transfer capability, integrated budgeting tools, and a unified financial dashboard

RESULTS:

4 banks integrated at launch, sub-2-second transfer completion, single dashboard managing all accounts

The Challenge: Before Intelegain

Decimal Finance was entering one of the most crowded fintech segments in India - UPI payments - where PhonePe, Google Pay, and Paytm collectively hold over 80% market share. To compete, the product needed to do something those incumbents did not: let users manage transactions across multiple banks with genuine budgeting intelligence, not just a transfer ledger.

The technical complexity was considerable. NPCI's UPI integration requires bank-specific SDK certification for each financial institution, with separate compliance validation processes that can take weeks per bank. Building for four simultaneously - while also delivering the consumer-grade UX that modern users expect - required fintech-specific engineering experience that Decimal Finance's internal team did not have.

NPCI UPI SDK integration is bank-specific and compliance-heavy

- requiring certified implementation per institution

Real-time transfer acknowledgment

demands sub-3-second end-to-end latency at P95 - a non-trivial infrastructure target

Multi-bank account aggregation required

secure credential storage and biometric authentication across sessions

No budgeting intelligence existed in Decimal's concept

- it needed to be designed from scratch with categorisation logic

Why the Decimal Finance Chose Intelegain

Decimal Finance ran a technical evaluation across four vendors. Intelegain's selection was driven by demonstrable fintech delivery history and specific architectural answers to the compliance challenge:

Prior UPI build experience:

Intelegain had navigated NPCI certification processes on a prior fintech engagement, meaning the compliance runbook - what documentation each bank requires, which SDK versions pass NPCI audit - already existed internally. This reduced the bank integration risk substantially versus vendors starting from scratch.

Security architecture depth:

Intelegain's proposal specified AES-256 encryption for stored credentials, certificate pinning against man-in-the-middle attacks, and biometric authentication tied to device-bound keys - a security posture that matched what Decimal Finance's compliance team required.

Consumer UX track record:

Intelegain shared two prior consumer fintech builds with documented App Store ratings above 4.3 - evidence that the team could ship security-critical code without sacrificing usability.

Implementation: The Intelegain Approach

Intelegain ran the build on a security-first principle: every feature requiring data persistence or bank communication was designed with the threat model in mind before the UI was drawn. The team structured delivery across four phases with bank integration running in parallel with the core app build to compress the timeline.

Phase 1: Compliance Architecture & UX Design

Documented NPCI compliance requirements for all four target banks. Designed the security architecture - key management, biometric auth flows, certificate pinning implementation. Produced UX wireframes for the transfer flow, account aggregation dashboard, and budgeting categorisation interface.

Phase 2: Core UPI Engine & Bank SDK Integration

Built the UPI transaction engine in parallel with bank-specific SDK integrations. Each bank integration ran through Intelegain's four-stage compliance checklist: sandbox testing, bank UAT, NPCI certification submission, production clearance. Integrated biometric authentication with device-bound key storage using Android Keystore and iOS Secure Enclave.

Phase 3: Budgeting Layer & Analytics Dashboard

Built the transaction categorisation engine using merchant category codes (MCC) supplemented by ML-based merchant name classification for non-MCC transactions. Delivered a monthly spend dashboard with category drill-down, budget threshold alerts, and recurring expense tracking across all linked accounts.

Phase 4: Security Audit, Performance Testing & Launch

Conducted penetration testing with a third-party security firm. Load-tested the transfer acknowledgment pipeline to validate sub-2-second P95 latency under 5,000 concurrent users. Deployed to App Store and Play Store with phased rollout for the first 30 days.

React NativeNPCI UPI SDKNode.js (API Gateway)PostgreSQLAndroid Keystore / iOS Secure EnclaveAWS Lambda

Measurable Results

Banks live at launch day

<2s

P95 transfer completion latency

4.4★

App Store rating at 30-day post-launch

40%

Security incidents in first 6 months

Building a fintech application that must pass compliance without missing launch dates?

Intelegain's fintech engineering team has navigated NPCI, RBI, and international payment compliance across multiple builds.

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