Poonkawin.dev - Poonkawin Saravanan — Python Backend Developer — poonkawin.dev
Available for backend & platform work

Building backend
systems that scale.

Production Python backend engineer — Django, PostgreSQL, multi-tenant SaaS and AI infrastructure.

Explore the journey →Read articles
P
Poonkawin Saravanan
Mallow Technologies · Coimbatore, IN
Users Cloudflare Nginx Django API schema-per-tenant Redis PostgreSQL Background Workers AI Services
API performance
60s→<0s

Endpoint response time, after fixing N+1 queries, indexes, query structure and a throttling burstable instance.

CI pipeline
45m→0m
Django test suite runtime — nine times faster.
Search
<0s
Down from 90s, once OpenSearch was sized for its heap.
Architecture
Multi‑tenant
Schema-per-tenant SaaS, live in production.
What I do

Four things I get called in for.

Backend Engineering

Django and FastAPI services with schema-per-tenant architecture.

Performance Engineering

Profiling, indexes, query structure and right-sized infrastructure.

AI Workflows

Led org-wide AI tooling evaluation. Leverage, reviewed line by line.

Developer Experience

Standards a client adopted unchanged, plus onboarding that sticks.

One request, end to end

Every hop is a place to lose a second.

0 ms U Users request in ~5 ms CF Cloudflare edge + TLS ~2 ms NG Nginx proxy ~20 ms DJ Django tenant routing ~1 ms RD Redis cache hit ~40 ms PG PostgreSQL indexed read async BW Workers queued async AI AI Services enrichment
Featured case study

A multi-tenant rebate platform, rebuilt from the inside.

Djangodjango-tenantsPostgreSQLRedisOpenSearchStripeAWS
01 · Problem

Inherited a client-built backend with no standards — and I was the only Django engineer on it.

~60s
Slowest endpoint responses
90s
Search, effectively unusable
1 dev
Only Django engineer on it
0
Standards in the inherited code
02 · Architecture

Schema-per-tenant on PostgreSQL. Isolation lives in the database, not in application code.

Tenant resolved from the subdomain, search path switched per request
Shared data isolated in the public schema
Same model mirrored in OpenSearch — one index per tenant
tenant-a tenant-b tenant-c django- tenants schema_a schema_b schema_c
03 · Implementation
Codebase standards
Standardized incrementally alongside feature work, so delivery never stalled.
Stripe payments
Webhook handling with idempotency and signature verification on every event.
Incentive engine
Rebate logic inside atomic transactions; concurrency resolved at the database.
Performance pass
N+1 removal, index correction, query restructuring, T-series → R-series.
04 · Impact
60s → <5s
Endpoint response time
90s → <2s
Tenant search latency
4 / 4
Root causes found and fixed
05 · Outcome

The client adopted my standards without a single change — and still runs on them.

Read the full case study →
Also shipped
Payments2024

Stripe Payment Integration

Built the Stripe payment integration for a multi-tenant SaaS platform — webhook-driven event handling, idempotency guarantees, and signature verification.

Reliable, idempotent payment processing with zero duplicate charges.
Performance2025

Database Performance Optimization

Partnered with the DBA team to diagnose and fix slow production endpoints — N+1 queries, missing indexes, inefficient queries, and undersized database infrastructure.

Endpoint response times cut from ~1 minute to under 5 seconds.
Search2025

OpenSearch Search POC

Proof-of-concept bringing OpenSearch into a multi-tenant platform, with an index-per-tenant design mirroring the PostgreSQL schema-based tenancy.

Sub-2-second search response after right-sizing infrastructure.
Data2023 — 2024

Amazon Sales Analytics

FastAPI application integrating the Amazon SP-API, with crawlers processing large-scale e-commerce data.

Automated ingestion and analysis of e-commerce sales data.
Internal2023

Trainee & Employee Management System

My first production Django system, built as an intern, replacing a hand-tracked trainee and employee records process.

Shipped internally.
Latest writing

Notes from production.

All articles →
AI15 min read

Stop Your AI Agent From Just Winging It — Use Superpowers

If you’ve used AI coding agents for a while, you’ve probably hit that frustrating moment where it just… starts writing code. No questions, no plan, just vibes.

Read article →
Django5 min read

Scaffolding Django + Inertia Projects in Seconds with create-django-inertia

create-django-inertia is a powerful CLI tool that generates a complete, production-ready Django + Inertia.js project structure in seconds. Choose your preferred frontend framework - React 18 or Vue 3 - and optionally add TypeScript support. The tool handles all the tedious setup - Django configurati

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Django4 min read

Inertia.js for Django: Build a Modern SPA Without a REST API

Learn how to build a modern single-page application (SPA) using Django and Inertia.js—without creating a REST API. A complete beginner’s breakdown with examples, benefits, and best practices..

Read article →
The journey

Intern to sole backend owner, in three years.

Jan 2023 — Jun 2023Mallow Technologies

Intern

An internal trainee and employee management system — my first real Django codebase.

First Django buildShipped internally
Jul 2023 — Jul 2024Mallow Technologies

Junior Developer

Amazon Sales Analytics on FastAPI: SP-API integration and crawlers for large-scale e-commerce data. My introduction to async, I/O-bound systems.

Amazon SP-APICrawler pipelinesFastAPI + async
Jul 2024 — PresentMallow Technologies

Python Developer

Sole Django engineer on a multi-tenant group-buying SaaS. Standardized the backend, built the Stripe and incentive modules, drove the performance work.

Sole backend ownerStandards adopted unchangedStripe + incentive engine60s → <5s
NowOrg-wide initiative

Building AI Developer Tooling

Led the evaluation of AI development tools across the organization — adopted deliberately, every generated line reviewed. Mentoring alongside it.

AI tooling evaluation leadMentoring & onboarding
Ecosystem

Four layers, one system.

BE
Backend
request handling
PythonDjangoFastAPIDRFCelery
IN
Infrastructure
delivery & runtime
DockerNginxGunicornAWSCloudflare
DB
Database
state & search
PostgreSQLRedisOpenSearchMongoDB
AI
AI
augmentation
ClaudeOpenAIMCPCursor
Currently exploring
AI coding agentsMCPOrcaOpenTelemetryObservabilityAI developer experience