Masterclass: Low-Level Design of Payment Apps – How Razorpay & PhonePe Build Secure Systems

Date: 18-02-2026 Time: 08:00 PM

Nischay

Senior Software Engineer - Criteria Corp | Ex - Signzy | Ex - EPAM | AWS Certified Developer Associate

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About Masterclass

In payment systems, correctness matters more than scale. A single bug can cause double debits, lost money, or inconsistent balances. This masterclass focuses on Low-Level Design (LLD) decisions behind payment apps like Razorpay and PhonePe - how services structure APIs, model transactions, manage concurrency, guarantee idempotency, and handle failures at the code and database level.

Masterclass Outcomes

API Design (Correctness First)
Transaction & State Modeling
Database Design (LLD View)
Concurrency & Idempotency Handling
Message Handling & Event Design
External System Integration (Bank/UPI)
Caching (LLD Rules)
Error Handling & Recovery
Logging, Auditing & Debuggability

Meet Our Host

Nishchay is a Senior Software Engineer at Criteria Corp with over 6 years of experience in software engineering, including full-time, internship, and freelance roles across MNCs and established startups. He is an AWS and Salesforce Certified Developer with strong expertise in building end-to-end full-stack applications. A B.Tech graduate in Information Technology from JECRC, he also holds certifications in Machine Learning, Cognitive Class AI, and Google Digital Unlocked. He is passionate about leveraging technology to solve real-world problems, create social impact, and continuously learn while collaborating with diverse teams.

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About Crio.Do

At Crio.Do, we believe that the best way to learn is by doing. Our mission is to empower aspiring developers and data enthusiasts through hands-on learning experiences that go beyond theory. Our unique approach combines real-world projects, industry-relevant skills, and expert-led guidance to prepare you for the challenges of today’s tech industry. Each Crio program is designed to help you build and master practical Software Development, QA Automation, and Data Analytics skills. Focusing on real-world scenarios and challenges, our programs ensure that you don’t just learn – you apply, build, and grow your abilities step-by-step.

Join our vibrant Alumni Network and embark on a journey that takes you from knowledge to experience, and from experience to expertise. At Crio, we’re not just teaching tech skills – we’re building careers

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