Backend Engineering
Django and FastAPI services on PostgreSQL, Redis, and Elasticsearch - 10,000+ concurrent requests at <200ms p95 on a 99.9% uptime SLA.
Django · FastAPI · PostgreSQLHi, I'm Lokendra Singh
I’m a solution-oriented engineer: the language and the framework are only the medium, and what counts is that the problem gets solved. Lead AI Engineer, Jaipur-based.
Stack: Python, Django, FastAPI, React, PostgreSQL, Kafka, RabbitMQ, Redis, Celery, Airflow, Druid, Superset, Snowflake, Docker, Kubernetes, Terraform, AWS, GCP, LLMs, RAG, LangGraph, LangChain, Langfuse, Multi-Agent Systems, Pinecone, ChromaDB, Neo4j, Elasticsearch, Computer Vision, YOLO, Claude Code, Cursor, MCP, Temporal.
Django and FastAPI services on PostgreSQL, Redis, and Elasticsearch - 10,000+ concurrent requests at <200ms p95 on a 99.9% uptime SLA.
Django · FastAPI · PostgreSQLRAG pipelines and multi-agent systems on LangChain and LangGraph over Pinecone, ChromaDB, and Neo4j - chatbots, personalised search, and workflow automation in production.
LangGraph · RAG · Vector DBsClaude Code, Cursor, and Copilot orchestrated behind mandatory review, automated tests, and architectural oversight - 40% faster delivery at production quality.
Claude Code · Cursor · CopilotKafka and RabbitMQ event backbones, Airflow and Druid pipelines, and deployments on AWS and GCP with Docker, Kubernetes, and Terraform.
Kafka · Airflow · AWS / GCPProblem, what I built, the outcome - and the trade-off I'd tell you about in the interview anyway.
Problem - students needed one place for courses, schedules, files and help, and every question waited for staff.
Built - a web, Android and iOS student app with LMS, Calendar and Drive integrations, an AI agent (PAC Agent, the Personal Academic Copilot) that helps with assignments and study, tells students their deadlines, and raises support tickets for technical issues and reports their status, also available as a ChatGPT plugin connected through MCP, and real-time chat; as team lead of 4 engineers.
Outcome - the platform was delivered in 20 days on web, Android and iOS, with AI-assisted coding across the stack.
Trade-off: AI-assisted coding bought the 20-day timeline; every change still went through review and tests, because speed without them is just faster bugs.
Problem - enterprise customer operations that needed AI automation able to hold up under real load, not a demo.
Built - event-driven microservices on Django, FastAPI, Kafka, PostgreSQL, Redis, Elasticsearch, and Neo4j, with LangChain/LangGraph RAG pipelines and multi-agent systems over Pinecone and ChromaDB.
Outcome - 5+ enterprise clients at 10,000+ concurrent requests under 200ms p95 on a 99.9% uptime SLA; support response time down 60%, ~$200K/year in operating cost removed.
Trade-off: two vector stores - Pinecone for the managed production path, ChromaDB for local iteration and evals - some duplication in exchange for not running vector infrastructure ourselves.
Problem - monitor and manage traffic across the Delhi–Mumbai Expressway in real time, with four-plus vendors' systems that didn't talk to each other.
Built - as Master System Integrator: a centralised event-driven pipeline on Django, React, Kafka, RabbitMQ, MySQL, and Airflow, integrating six AI/CV modules - VIDS, VSDS, VMS, ANPR, ADAS, and pothole detection.
Outcome - live across 580+ km on three corridors - Sohna–Dausa, Delhi–Vadodara, Vadodara–Mumbai; incident response time down 40%. Demonstrated to Union Ministers and the Haryana CM in Feb 2024, unlocking $2M+ in expansion.
Trade-off: prioritised operator-verified alerts over full automation - fewer false dispatches at the cost of some latency on edge cases.
Problem - toll plazas across India going down with no central view of their health - every outage was lost revenue.
Built - a pan-India IoT platform aggregating real-time health data from 1,500+ plazas into a toll data lake on AWS (RDS, S3) with Apache Druid, Airflow, Superset, and custom ETL, feeding integrated analytics and automated ticketing.
Outcome - 1,500+ toll plazas monitored; toll downtime down 30% (~$500K/year in recovered revenue), issue resolution 50% faster.
Trade-off: ran Druid and custom ETL on AWS instead of a managed warehouse - more to operate, but full control over ingestion from 1,500+ heterogeneous plaza feeds.
Problem - 9XM wanted its Bade Chote jokes on Amazon Alexa, so listeners could ask a smart speaker for a joke by voice.
Built - an Alexa skill that hears the request and answers with a Bade Chote joke, with the server set up and the skill deployed and maintained end to end.
Outcome - the skill went live on Amazon.in, published under 9XM.
Problem - employees hunted through documents and emails for company policies, and every leave request, timesheet change or HR question became a ticket or a message to HR.
Built - a company-wide AI agent that answers from company policies, applies for leave, updates timesheets and handles other HR requests, on durable workflows (Temporal, LangGraph) that connect to company systems through MCP and A2A.
Outcome - one assistant for policies, leave, timesheets and HR requests, with multi-step requests that resume exactly where they stopped through deploys and failures.
Trade-off: Temporal's determinism constraints shape how agent code is written - a learning curve traded for replayable, auditable runs of every request.
Problem - 1,000+ Self-Help Groups across rural Chhattisgarh (CGSRLM, with Pradan) collecting financial data where connectivity can't be assumed.
Built - an offline-first Android app with sync and conflict resolution, plus a centralised analytics layer on Django, PostgreSQL, Druid, Airflow, and Superset.
Outcome - data-driven benefit distribution to 50,000+ beneficiaries; processing time down 40%.
Trade-off: offline-first means every record can be edited in two places - sync with explicit conflict resolution costs UX complexity, but never silently loses a field worker's data.
Problem - a one-to-one tuition marketplace that had to screen thousands of teachers and match each student to the right one, across teachers, parents and students.
Built - web and mobile apps for all three groups, an admin panel for teacher screening, and a verified pre-onboarding checklist; I owned code review, deployment and architecture.
Outcome - a network of 40,000 teachers and 25,000 students across 200 institutions, with a 98% student success rate.
Trade-off: a strict onboarding checklist slows teacher sign-up - accepted, because the platform's reputation is the quality of its teachers.
Problem - 56 Secure’s apps on Android, iOS and the web each needed to work with network video recorders, through APIs owned by the recorder maker’s team in China.
Built - an NVR SDK: one integration layer over the recorder APIs, built into all three apps, with the solution architecture and the production servers on AWS; as lead engineer and solution architect.
Outcome - the SDK shipped inside 56 Secure’s base app on Android, iOS and web.
Problem - people who see an accident needed a way to report it anonymously, with live video from the scene.
Built - the app’s backend from scratch, its APIs, dynamic pages, and live video streaming through AWS Kinesis, for Inkers Technology.
Outcome - accidents reported anonymously with live video, in an app built from scratch.
Problem - farmers’ data in Odisha had to be collected in one place and turned into analytics.
Built - the backend from scratch, the APIs for data collection and analytics, and deployments to staging and live.
Outcome - farmer data collected and shown as analytics on one platform.
Problem - an in-house idea needed a working product: a website where people could adopt plants online.
Built - the backend from scratch, its APIs, fixes on the React front end, and deployments to staging and live.
Outcome - the platform went live with its backend, APIs and front end in place.
Problem - several hospital vendors needed one system, with different access for patients, doctors and staff.
Built - a multi-vendor hospital platform on Django with DRF APIs, role-based logins, live video streaming and dynamic pages, for Inkers Technology.
Outcome - one platform with separate logins for patients, doctors and staff, built from scratch.
Problem - a client needed to take Amazon Pay payments from a Python backend.
Built - a Python payment SDK for Amazon Pay, built from scratch in Flask after gathering the requirements with the client.
Outcome - a Python SDK for Amazon Pay, delivered to the client’s spec.
Where I take the newest open models end to end, on my own hardware.
One request in the admin panel, and a song, story, video, image or social post comes out, with every heavy model taking its turn on one RTX 5060 Ti.
Tools I build in public on GitHub. Small, documented, and meant to be used.
Share a note as a link, with nothing saved anywhere. The link is the note.
Notes from production - agentic systems, durable workflows, and what actually breaks at scale.