ASAbhishek Shukla

Backend engineerFounding team · GetMySaaS.aiIndia · 2026

AbhishekShukla

I design payment flowsevent pipelinesAPIssystems, then I build them. Payments, billing and events on the backend, and the app in your hand.

Try to break my payment system→

01 · What I do

I build the partyou never see.

  • 0services I helped build at GetMySaaS, in Java 21 and Spring Boot: product, vendor, consumer, cart, payment, subscription, auth, pricing
  • 0products taken from zero: as an early engineer at GetMySaaS.ai, and on my own for Flow Glasses
  • 0test files in my UPI reconciliation lab, including Testcontainers on real PostgreSQL

02 · How I build

Four rules. The console below proves them.

  1. 01 · architecture

    Start with one clean backend

    A new product starts as one well-structured backend, and splits only when it earns it.

  2. 02 · trust

    Trust the provider, not the client

    Payment status comes from signed webhooks. A browser redirect proves nothing.

    see it ↓
  3. 03 · retries

    Expect every retry

    Providers send events twice. Anything that touches money is idempotent.

    break it ↓
  4. 04 · observability

    Make it observable

    If you can’t trace a request across the system, you can’t fix it quickly.

    watch the log ↓

03 · Chaos console

Break it. It holds.

This is the payment flow from my UPI reconciliation lab, running in your browser. The gateway misbehaves on purpose, the way the repo’s simulator does: every webhook arrives three times, a stale failure follows every success, some webhooks never come. Try to get an order paid twice.

idle

Pick a scenario, or place an order.

idle · no traffic

Nothing is running yet.Pick a scenario on the right, or place an order, to send the first request through the system.

      A browser simulation of the design in abhishek1913/upi-checkout-reconciliation ↗. The real service does this against PostgreSQL, with the concurrency tested in Testcontainers. The repo drops webhooks for about 1 in 10 payments; free play uses 1 in 4 so you see it. More systems to break on Architecture Lab ↗.

      04 · Work & labs

      The app you see. The system you don’t.

      01 Professional · Mar 2025 to now

      GetMySaaS.ai

      Founding backend engineer

      A SaaS marketplace backend built from scratch, from the first services to payments, billing and subscriptions in production.

      • Helped build eight services in Java 21 and Spring Boot
      • Stripe and Lago, idempotent end to end
      • Kafka with CQRS and event sourcing
      GetMySaaS.ai home page

      move across the screen to x-ray it

      02 Lab · open source

      UPI Checkout & Reconciliation

      Placed to paid, even when webhooks lie

      One tap on the phone. Behind it, webhooks that arrive twice, late, out of order or never, and an order that is still paid exactly once.

      • Idempotent webhook inbox
      • Reconciliation with FOR UPDATE SKIP LOCKED
      • 48 test files, Testcontainers on real PostgreSQL
      You already tried to break this one ↑
      UPI checkout screenPENDING
      1. POST /orders · Idempotency-Key k_8c1 · attempt INITIATED
      2. PAYMENT_SUCCESS evt_7f3a · signature ✓ · applied
      3. same event, again · ON CONFLICT · skipped
      4. same event, a third time · skipped
      5. stale FAILED · older than the success · ignored
      6. 1 transition · paid once

      03 Lab · open source

      TrustLayer

      Access decided on the server

      1. RegisterUSER_REGISTERED, announced only after the commit
      2. Verify emailSingle-use, hashed, expiring token
      3. Verify identityThe provider’s signed webhook says so, not the browser
      4. Pay, and come backReturning from Stripe proves nothing on its own
      5. Signed webhookcheckout.session.completed, verified on the raw body
      app/dashboardBLOCKED

      BLOCKED0 of 4 checks

      • Email verifiedlocked
      • Identity verifiedlocked
      • Payment succeededlocked
      • Subscription activelocked
      browser → /payment/successstill BLOCKED · waiting for the signed webhook

        04 Contract · May to July 2026

        Flow Glasses

        Backend and mobile · the only engineer

        Smart glasses, a phone app and an AI backend, built end to end in three months with no team to hand decisions to. Every box in this chain was mine.

        • Architecture and data model
        • Backend APIs and the AI integration
        • The React Native app and every release
        smart glasses
        device link

        Flowglasses connected

        Listening…Ask your glasses anything. The answer comes back through the AI backend.

        react native app
        API
        BackendAPIs · logic · data
        AI servicethink and answer
        every box: mine
        1. voice in
        2. to the app
        3. backend → AI
        4. answer back

        app screen is illustrative until real captures are in

        05 Client work · website

        KHASKEL

        [Your role · to confirm]

        The website for a founder-led destination wedding planner in North Bengal, across Darjeeling, Kalimpong, the Dooars and Siliguri.

        Visit khaskel.com ↗
        khaskel.com home page

        05 · Labs I run

        I also build places to learn this.

        Two learning platforms I designed and built, where system design is something you run, break and predict instead of memorise.

        architecture.abhishekshukla.onlineopen ↗
        Software Engineering Architecture Lab home

        Architecture Lab

        How real systems are designed, evolved, scaled and repaired.

        0lessons
        0simulations
        0case studies
        0books, one path

        You follow one fictional company, ShopFlow, from a one-developer Spring Boot monolith to a multi-region platform run by ninety engineers. At every step you feel the pain first, then meet the idea that relieves it, and what that idea costs.

        06 · Stack

        Tools, and where they ran.

        Point at a tool to see which systems use it, or at a system to see its stack.

          07 · Experience

          git log --graph

          1. HEAD → main · 2025 — now

            GetMySaaS · SDE 1, founding backend team

            End-to-end ownership of backend systems, from architecture and development to production: microservices on Kafka with CQRS and event sourcing, Stripe and Lago, long-running workflows, tracing on Kubernetes and AWS, production debugging and incidents.

          2. merge contract/flow-glasses · May — Jul 2026

            Flow Glasses · Contract, backend and mobile

            A smart-glasses product end to end on my own, from the database to the mobile app. Deployed the backend and handled releases as the only engineer.

          3. May 2025

            GetMySaaS · Backend developer intern

            REST APIs with Spring Boot and PostgreSQL to production, a working prototype of the payment service, unit and integration tests with JUnit and Mockito.

          4. initial commit · Mar — Apr 2025

            GetMySaaS · Founder’s office intern

            Early groundwork: set up domain and email, researched and evaluated stacks for the backend and infrastructure.

          08 · Writing

          Aug 12, 2024 · 8 min

          Why CQRS Changed How I Think About Scale

          “Your read model doesn’t have to look like your write model.”
          ↗

          Sep 05, 2024 · 12 min

          Lessons from Running Microservices in Production

          “Then you deploy to production. And you learn things that no architecture diagram ever taught you.”
          ↗

          09 · Contact

          Let’s build something.

          Founding-team backend: payments, billing, event-driven systems, and the app on top. I’m open to opportunities.

          POST /v1/hire HTTP/1.1
          Host: abhishekshukla.onlineContent-Type: application/jsonIdempotency-Key:
          { }
          opens your mail app with this message