How Does UPI Actually Work Behind the Scenes?

prakash raj — Wed, 15 Jul 2026 18:34:46 +0000

Most of us use UPI every day.

We scan a QR code, enter a PIN, and within a few seconds, the payment is complete.

But have you ever wondered what actually happens between tapping Pay and seeing Payment Successful?

There are several systems working together behind the scenes:

How your UPI ID is resolved to the correct bank
Why your payment app never sees your actual UPI PIN
How NPCI routes transactions between banks
How debit and credit happen almost simultaneously
The security mechanisms that protect every transaction

I recently did a deep dive into the complete payment flow—from NEFT, RTGS, and IMPS to the architecture that powers modern UPI payments.

If you're interested in fintech, distributed systems, backend engineering, or payment infrastructure, you might find it interesting.

👉 Read the full article here:

http://medium.com/p/eb3632d8c021

I'd also love to hear your thoughts:

What part of UPI's architecture surprised you the most?
Are there other large-scale distributed systems you'd like to see broken down in a similar way?

I Built a Python CLI Because I Kept Forgetting the Reasoning Behind My Code

prakash raj — Wed, 15 Jul 2026 18:29:53 +0000

I Built a Python CLI Because I Kept Forgetting the Reasoning Behind My Code

As developers, we spend a lot of time solving problems.

We debug production issues, optimize performance, refactor legacy code, and make dozens of architectural decisions throughout a project.

The problem is that a few months later, it's surprisingly difficult to remember why we made those decisions.

You might remember that you added Redis, introduced caching, changed an API, or optimized a database query—but remembering the reasoning, trade-offs, and impact behind those changes is much harder.

That became obvious to me whenever I prepared for interviews or updated my resume.

I could remember what I built, but questions like these were much harder to answer:

Why did I choose this approach?
What alternatives did I consider?
What problem was I actually solving?
What was the impact of this work?
What did I learn from implementing it?

Most of that context existed only in my head—and eventually, I forgot it.

The Idea

Instead of trying to reconstruct those details months later, I thought:

Why not capture them immediately after finishing the work?

That idea became QuickSnap, a Python CLI that helps capture the context behind your engineering work while it's still fresh.

Installation

pip install quicksnap

Example Workflow

After completing a feature or bug fix:

quicksnap capture

View everything you've captured:

quicksnap list

Search previous work:

quicksnap search "redis"

Generate a STAR interview story:

quicksnap star auth-refactor

Create resume bullet points:

quicksnap bullets auth-refactor

Practice interview questions based on your own engineering work:

quicksnap practice

Why I Built It

My goal wasn't to replace Git, documentation, or project management tools.

It's simply a lightweight way to preserve the engineering context that's easy to lose over time.

Later, instead of trying to remember what happened months ago, I can search my own work and instantly recall:

The problem I solved
The reasoning behind the solution
The trade-offs I made
The outcome
The lessons I learned

I'd Love Your Feedback

This project is still evolving, and I'm actively improving it.

Some ideas I'm exploring include:

Better search
IDE integrations
Git hooks
Team knowledge sharing
Additional export formats

If you've ever struggled to remember the context behind your own work, I'd love to hear how you solve that problem.

You can check out QuickSnap on PyPI:

https://pypi.org/project/quicksnap/

Feedback, suggestions, and feature requests are always welcome.

DEV Community: prakash raj

How Does UPI Actually Work Behind the Scenes?

I Built a Python CLI Because I Kept Forgetting the Reasoning Behind My Code

I Built a Python CLI Because I Kept Forgetting the Reasoning Behind My Code

The Idea

Installation

Example Workflow

Why I Built It

I'd Love Your Feedback