Fractional CTO for
Commerce & Quick-Commerce.
I help commerce and quick-commerce founders build reliable ordering, inventory, and checkout systems that stay online during traffic surges. As your fractional CTO, I fix stock discrepancies across dark stores and stop phantom inventory from eroding buyer trust. You get battle-tested architecture that scales smoothly while keeping your engineering overhead lean.
01 HIGH-CONCURRENCY PAINS
5 critical founder bottlenecks
I resolve permanently.
Early technical shortcuts create hidden liabilities that compound as order volume scales.
Phantom Stock & Overselling Across Dark Stores
Your storefront displays products that warehouse pickers cannot find on physical shelves. Buyers place orders for out-of-stock items, forcing expensive cancellations and refunds.
Cart Failures During Flash Sales & Promotions
Surges in concurrent buyers cause database locks and unresponsive checkout buttons. Shoppers abandon their carts right when purchase intent peaks, wasting your marketing budget.
Leaky Coupon Engines & Stacking Loopholes
Buyers combine promotional codes in unintended combinations. Your checkout fails to enforce strict basket limits or user exclusions, draining margins on every order.
Fulfillment Disconnect Between Storefront, Warehouse & Riders
Warehouse staff rely on delayed screens or manual paper picklists. Pickers waste precious minutes searching aisles while delivery riders idle outside dark stores.
Slow Mobile Checkout Flows Hurting Conversion
Bloated tracking scripts and unoptimized backend endpoints delay payment screens. Mobile shoppers drop off before completing transactions due to frustrating friction.
02 CORE SPECIALIZATIONS
What I build, audit,
and optimize.
Production systems engineered in Go, PostgreSQL, Redis, and edge event streaming.
Order Management System (OMS)
I build state machine engines in Go and PostgreSQL to coordinate the entire order lifecycle. The system manages deterministic transitions across payment verification, dark store packing, rider handoff, and delivery confirmations. It processes payment callbacks idempotently and broadcasts instant status updates to customer applications.
High-Concurrency Cart & Ephemeral Reservations
I implement in-memory reservation engines using Redis lease locks and time-to-live expirations. When a shopper adds an item, stock reserves temporarily for ten minutes. If the shopper abandons the basket, stock releases automatically to the catalog. This stops overselling without locking relational database rows.
Rule-Based Coupon & Promotion Engine
I create coupon rule engines that validate basket criteria in real time. We support minimum order values, catalog category restrictions, user usage limits, and anti-abuse safeguards. The engine prevents unauthorized coupon stacking and protects gross margins.
Warehouse Inventory Allocation Across Dark Stores
I design two-phase inventory reservation protocols for multi-hub retail networks. The system splits catalog availability into available-to-promise inventory and physically allocated items. Stock levels update continuously across warehouse stations, ensuring shoppers only see products ready for immediate packing.
High-Speed Checkout & Payment Orchestration
I engineer checkout pipelines with automatic payment gateway failover and duplicate-charge protection. Idempotency tokens ensure network retries never charge buyers twice. Shoppers enjoy fast, seamless payment flows on mobile devices.
03 FOUNDER-FRIENDLY MENTAL MODEL
Simple Architecture (For Non-Technical Founders)
Think of your commerce system like a busy bakery counter with an orderly queue.
When a shopper adds a loaf of bread to their cart, my system places a temporary reservation tag on it. No other customer can touch that specific loaf while the timer counts down.
If the customer completes checkout, the bread moves directly to the packing table. If the customer walks away, the timer expires and the bread returns to the open shelf.
Behind the scenes, your warehouse packing screen receives an aisle-sorted picking list instantly. As soon as the bag is sealed, the system summons the delivery driver outside.
Every step follows automated rules, so your operations stay reliable without manual panic.
04 FOR YOUR ENGINEERS
Technical blueprint &
system data flows.
Architectural component topology and event boundaries.
flowchart TD
Client[Web & Mobile Clients] --> Edge[Cloudflare CDN & Rate Limiter]
Edge --> APIGW[API Gateway - Envoy / Go Proxy]
subgraph Core Commerce Services
APIGW --> CartSvc[Cart & Pricing Service - Go]
APIGW --> OMSSvc[Order Management Service - Go]
APIGW --> PromoSvc[Promotion Engine - Go]
end
subgraph In-Memory Caching & State
CartSvc --> RedisCluster[(Redis 7 Cluster - Ephemeral Lease Locks)]
PromoSvc --> RedisPromo[(Redis 7 - Rule Cache)]
end
subgraph Persistent Storage
OMSSvc --> PostgresPrimary[(PostgreSQL 16 - Order Ledger)]
PostgresPrimary -.-> PostgresReplica[(PostgreSQL Read Replicas)]
end
subgraph Event Streaming & Fulfillment
OMSSvc --> Kafka[Apache Kafka Event Bus]
Kafka --> WMSWorker[WMS Dispatch Worker]
Kafka --> NotifWorker[Customer Notification Worker]
Kafka --> DataWorker[Analytics Sync Worker]
end
subgraph Dark Store Operations
WMSWorker --> DarkStoreApp[Picker Mobile / Tablet App]
DarkStoreApp --> LogisticsHub[Last-Mile Dispatch Gateway]
endEnd-to-End Data Flows
The client sends POST /cart/items with a unique idempotency key. The Cart Service executes an atomic Redis Lua script verifying available stock and placing a 10-minute lease lock.
The client requests checkout. The OMS creates an order record in state PENDING_PAYMENT in PostgreSQL. An idempotency token registers in Redis with a 15-minute lease.
The payment gateway issues a webhook callback. The handler verifies the cryptographic HMAC signature and transitions the order state to CONFIRMED.
On confirmation, the OMS publishes an order.confirmed event to Apache Kafka. The warehouse worker consumes the event and generates an aisle-optimized picklist for the tablet.
When the picker scans the final barcode, the status updates to PACKED, and the system immediately summons a nearby delivery courier.
Storage Engines & Data Partitions
- Redis 7 (Cluster Mode): Ephemeral cart reservations, rate limiters, and session states.
- PostgreSQL 16: Relational order database partitioned by store_id and order date.
- Apache Kafka: Decoupled event log across order lifecycle changes and analytical pipelines.
- OpenSearch: Search engine for fast catalog lookups and faceted product filtering.
Engineering Design Targets
- Cart Reservation Latency: Design target under 25ms at peak traffic.
- Stock Overselling Rate: Design target of zero oversold items during high-volume drops.
- Webhook Acknowledgment Time: Design target under 50ms.
05 VERIFIED PEDIGREE
Former Engineering Manager at Blinkit (Part of Eternal, formerly Zomato)
- Engineered high-throughput dark store picking workflows, catalog replenishment systems, and inventory pipelines.
- 12+ years of engineering experience delivering distributed commerce systems.
- Open-source author of backend Go toolkits at github.com/Abeta-dev (including go-libs and go-app-kit).
06 TRANSPARENT PRICING
Single source of truth
pricing & engagements.
Transparent pricing without hidden fees or forced long-term lock-in.
| Engagement Tier | Investment | Scope & Terms |
|---|---|---|
| Architecture Teardown | $1,500 / AED 5,500 / INR 1.25L | 48-hour diagnostic teardown identifying immediate scaling bottlenecks. |
| Architecture Audit | $5,000 | 5-day deep code, database, and cloud audit. 100% credited to any follow-on sprint. |
| Advisory Fractional CTO | $6,000 / month | Strategic steering, architecture roadmaps, and PR reviews. 3-mo min, then 30d notice. |
| Core Fractional CTO | $12,500 / month | Hands-on technical leadership, hiring rubrics, and sprint management. 3-mo min, then 30d notice. |
| CTO + Senior Pod | $35,000 – $48,000 / month | Executive CTO leadership paired with senior systems engineers. 3-mo min, then 30d notice. |
| Build Sprints | From $45,000 | Milestone-based platform development from architecture to live production. |
07 QUESTIONS & ANSWERS
Frequently asked
questions.
How do you prevent stock overselling during flash sales?
I use Redis Lua scripts to execute atomic stock checks with time-limited leases. Units reserve in memory before payment starts, preventing double-selling.
Should we replace Shopify with a custom engine?
Stick with Shopify if standard features meet your needs. Build custom software when dark store routing or unique cart rules demand greater flexibility.
How does the system handle missing or damaged warehouse items?
When a picker reports a damaged item, the system triggers a micro-reallocation. It attempts auto-substitution or updates the invoice before rider dispatch.
How quickly can you audit our current commerce codebase?
My 5-day architectural audit takes one business week. You receive a complete bottleneck evaluation, architectural diagrams, and an actionable sprint roadmap.
What tech stack do you recommend for custom commerce platforms?
I recommend Go and PostgreSQL for core backend services, Redis for high-speed reservations, and Next.js or React Native for client apps.
How do you work with our existing engineering team?
I act as your fractional CTO. I establish architectural patterns, review pull requests, eliminate delivery roadblocks, and guide sprint planning directly.
08 GET STARTED
Solidify your architecture
before traffic surges.
Book a direct 20-minute video session with software architect Umesh Gupta. Response promise: same business day (IST).