Associate Technical Lead · Backend & AI Engineering

I build backend and AI systems that hold up in production.

I'm Sachin, an engineer with 6+ years across enterprise backend, distributed and AI-enabled systems. I work in Python, FastAPI, Django, Java, PostgreSQL and AWS, and I own features from architecture through deployment and production support. Today I lead backend and AI engineering at Gapstars for Envision Pharma Group.

Get in touch See my work

LinkedIn ↗ GitHub ↗ Upwork ↗ Medium ↗

Colombo, Sri Lanka

6+years building software

100%Job Success on Upwork, Top Rated

5peer-reviewed publications

2025Kim Cameron Award recipient

What I do

Most of my work sits where backend reliability, cloud infrastructure and applied AI meet.

Backend & distributed systems

REST APIs, data models and background processing designed for retries, caching, idempotency and failure recovery.

Python
FastAPI
Django / DRF
Java
Spring Boot
PostgreSQL
Redis
Celery

Applied AI engineering

RAG, grounded generation, AI agents, tool calling, structured outputs and evaluation, built into real product workflows.

LangGraph
LangChain
Claude
OpenAI
Gemini
pgvector

Cloud & platform

Services on AWS EKS and Kubernetes, shipped through CI/CD and watched with proper observability.

AWS
EKS
Kubernetes
Helm
Terraform
GitHub Actions
Dynatrace
Logfire

Identity & security

B2B customer identity, multi-tenancy and secure integrations, from nearly four years on WSO2 Identity Server.

OAuth 2.0
OIDC
SAML
mTLS
Webhooks
Multi-tenancy

Experience

Jan 2026 – Present

Associate Technical Lead, Backend & AI Engineering

Gapstars · Client: Envision Pharma Group

Lead design and hands-on development of production backend and AI services with Python, FastAPI, PostgreSQL, Redis and Celery on AWS EKS.
Build AI manuscript-drafting workflows using RAG, grounded generation, tool calling, structured outputs and evaluation.
Own features from requirements to production verification, including Helm-based worker deployments monitored with Dynatrace, Sentry and Logfire.
Lead architecture discussions and PR reviews, and mentor engineers.

FastAPI
PostgreSQL
Celery
EKS
RAG

Feb 2024 – Dec 2025

Senior Software Engineer

WSO2

Led development of enterprise backend and multi-tenant systems in Java, Spring Boot, Python and Django.
Designed secure webhook management and event-driven integrations, including mTLS and asynchronous WebSubHub publishing.
Profiled identity-service and database bottlenecks with JMeter and JProfiler, then improved queries, indexing and sessions across AWS environments.
Built Angular and TypeScript interfaces, reviewed code and mentored engineers.

Java
Spring Boot
Django
Angular
AWS

Mar 2022 – Feb 2024

Software Engineer

WSO2

Built backend services and multi-tenant APIs with Java, Spring Boot, Python and Django REST Framework.
Developed Organization Management, B2B CIAM and integrations using OAuth 2.0, OIDC, SAML and adaptive authentication.

OAuth 2.0
OIDC
SAML
CIAM

2026 – Present

Independent AI & Backend Consultant

Upwork

Top Rated, with 100% Job Success and 500+ hours delivered across AI agent engineering, backend systems and enterprise integrations.

Aug 2023 – Present

Visiting Lecturer

University of Moratuwa

Teach Business Intelligence and Analytics to final-year undergraduates, design assessments and evaluate research projects.

Jul 2020 – Jan 2021

Software Engineering Intern

CodeGen International

Built user-behaviour tracking for an enterprise chatbot, and SLA monitoring for a Jira-integrated project-management platform.

Selected projects

Open-source work and research outside my day job.

Multilingual WhatsApp RAG agent

A multi-tool agent that routes each question to a PDF knowledge base, web search or conversation memory, and answers in English, Sinhala or Tamil for safety and hazard awareness.

RAG
Agents
Azure Container Apps

View on GitHub →

Multi-agent starter kit

A monorepo starter for multi-agent systems on LangGraph, with a FastAPI backend, Typer CLI, Next.js 15 UI and a PostgreSQL checkpointer.

LangGraph
FastAPI
Next.js
PostgreSQL

View on GitHub →

TrustworthyCodeLLM

An evaluation framework for code LLMs that scores security, robustness, maintainability and communication using execution tests, static analysis and LLM-ensemble judging.