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Lalit Kumar
Verified Expert in Engineering
Go Developer
Bengaluru, Karnataka, India
Toptal member since September 2, 2026
Bio
Lalit is a senior engineer with 5 years of experience building production systems from scratch in high-stakes environments. As a founding engineer at 021 Trade, he crafted a SEBI-registered stock brokerage's tech stack, achieving 5–10x latency and infrastructure gains over existing vendor systems. Lalit also developed RAG-powered AI tools, a multi-tenant SaaS platform, and a Reddit monitoring tool that organically scaled to 10,000 concurrent users.
Portfolio
Digital Visibility Concepts
Node.js, Next.js, PostgreSQL, AI Automation, TypeScript, JavaScript, SQL...
021 Trade
Go, PostgreSQL, Node.js, Docker, Next.js, Product Management, Flutter...
Weekday
Node.js, Product Management, TypeScript, JavaScript, SQL, CRM, Chrome DevTools...
Experience
- Go - 4 years
- TypeScript - 4 years
- WebSockets - 3 years
- Multi-tenant SaaS - 3 years
- Low-latency Software - 3 years
- Fintech - 3 years
- Next.js - 3 years
- AI Automation - 2 years
Work Experience
Founding Product Engineer
2026 - PRESENT
Digital Visibility Concepts
- Built a visitor-identification and remarketing SaaS platform end-to-end in Express.js and Next.js, featuring a multi-tenant dashboard, real-time visitor resolution, AI-generated outreach, and compliance-filtered reporting. Shipped MVP in 2 weeks.
- Cut visitor identification from 24 hours (batch pipeline) to instant identification by engineering a custom pixel to identify visitors in real time.
- Reduced errors shipped to clients by 75–80% and saved 2+ hours of manual work daily by automating data ingestion, compliance validation, enrichment, and report generation pipelines.
- Developed a client-facing multi-tenant dashboard from scratch, featuring tenant-isolated data views, visitor analytics, and outreach tracking—architected for multi-client onboarding from day one.
- Built an AI-powered daily outreach generation (Claude API) producing prioritized call, email, and mailed letter lists — each contact scored by a deterministic model evaluating intent, engagement, and demographic signals.
- Architected the data pipeline from raw visitor ingestion through identity resolution, compliance checks, and filtered daily reporting, ensuring outreach lists met regulatory requirements before delivery.
- Set up full AWS infrastructure, including EKS for container orchestration and EC2 for compute, with CI/CD via GitHub Actions for automated testing and deployment.
- Owned the entire product lifecycle as sole engineer, handling architecture, implementation, deployment, and monitoring, while shipping the MVP in 2 weeks and iterating directly from founder briefs.
Technologies: Node.js, Next.js, PostgreSQL, AI Automation, TypeScript, JavaScript, SQL, Express.js, Microservices, Event-driven Architecture, Data Pipelines, Tailwind CSS, Redux, JSON Web Tokens (JWT), Role-based Access Control (RBAC), Multi-tenant SaaS, Multi-tenant Architecture, Code Review, Debugging, Back-end Development, Chrome DevTools, Web Standards, Web Development, Full-stack, APIs, Agentic AI, Artificial Intelligence (AI), Cloud Architecture, Databases, DevOps, Technical Leadership, API Integration, Dashboards, MVP Design, Application State Management, Responsive UI, User Experience (UX), User Interface (UI), System Integration, Software Architecture, Claude, Claude Code, Vibe Coding, Consulting, Training, WordPress, Front-end Development, Web Design, Technical Writing, Docker, React, Real-time Data Pipelines, Claude API, Integration, Large Language Models (LLMs), REST APIs, Workflow Automation, Workflow Automation & System Integration, SaaS, Software as a Service (SaaS), Privacy, Security, Supabase, Full-stack Development, Web Application Architecture, AI Agents, AI Integration, Front-end, SSG, Server-side Rendering (SSR), Zod, LLM Agents, AI-assisted Development, AI-generated Code, Integrations, ETL, ETL Pipelines, ETL for AI
Founding Engineer
2022 - 2026
021 Trade
- Served as the founding engineer at a SEBI-registered stock brokerage, building the entire tech stack from the first commit, including OMS, market data, KYC, web and mobile apps, and bare-metal infrastructure; grew the team to 12 over 3 years.
- Grew from intern to leading the team in under 3 years by hiring, training, and retaining a 12-person team as the company scaled from the founding stage to 25+ employees.
- Designed a highly available order management system that cut exchange failover downtime by 10x compared to vendor systems, routing orders to exchanges via FIX protocol and optimizing for high-throughput, low-latency processing with Kafka-based messaging.
- Built a real-time high-availability market data pipeline ingesting 30–45,000 ticks/second from exchanges with automated failover and internal fan-out to downstream services via custom protocols and throttling.
- Achieved 25x better connection efficiency per vCPU than vendor systems by building the WebSocket layer for real-time data delivery, featuring connection pooling, efficient batching, and horizontal scalability.
- Built a position-aware GTT engine supporting linked intraday target/stoploss orders with real-time trigger execution, a capability absent from major Indian brokers at the time.
- Improved Lighthouse performance from 70 to 95+ by migrating the web app from React to Next.js, enhancing order placement, watchlists, charts, live data, and portfolio views.
- Reduced mobile app cold-start from 15–30s to under 2s and eliminated frame drops by revamping the Flutter app's market data rendering pipeline; shipped in under 2 months.
- Deployed all infrastructure on bare-metal servers in a co-located data center with N+1 redundancy at every layer, including exchange leased lines, servers, and databases.
- Built a fully automated KYC onboarding pipeline with Digilocker, CKYC, and KRA verification via Digio middleware, featuring internal QA workflows, client communication layers, and a CRM for tracking onboarding status, with a final human QA step before approval.
Technologies: Go, PostgreSQL, Node.js, Docker, Next.js, Product Management, Flutter, WebSockets, TypeScript, JavaScript, Python, SQL, Express.js, Microservices, Event-driven Architecture, Redis Cache, MongoDB, Data Pipelines, Tailwind CSS, Redux, Low-latency Software, JSON Web Tokens (JWT), Role-based Access Control (RBAC), Multi-tenant SaaS, Multi-tenant Architecture, Concurrency Patterns, Multithreading, Dart, Code Review, Debugging, Back-end Development, Trading, React, Financial Markets, Fintech, Real-time Data, CRM, Chrome DevTools, Web Standards, Web Development, Cross-browser Compatibility, Full-stack, APIs, Agentic AI, Artificial Intelligence (AI), Cloud Architecture, Databases, DevOps, Technical Leadership, Distributed Systems, API Integration, Dashboards, MVP Design, Application State Management, Jest, Responsive UI, User Experience (UX), User Interface (UI), Zapier, System Integration, n8n, AI Automation, Software Architecture, Claude, Claude Code, Consulting, Training, WordPress, Front-end Development, Web Design, Technical Writing, Real-time Data Pipelines, Claude API, Integration, OAuth 2, REST APIs, Workflow Automation, Workflow Automation & System Integration, Finance, SaaS, Software as a Service (SaaS), Performance, Privacy, Security, Supabase, Full-stack Development, Web Application Architecture, AI Agents, AI Integration, Front-end, Responsive Web Apps, SSG, Server-side Rendering (SSR), React Query, Zod, LLM Agents, AI-assisted Development, AI-generated Code, Integrations, ETL, ETL Pipelines
Back-end Engineer (Founders Office)
2021 - 2022
Weekday
- Built the back end, automations, and growth engine for a referral marketplace connecting 100+ active tech recruiters with candidates.
- Grew the referral marketplace to 65% MoM growth across 100+ active recruiters, reaching thousands of monthly referrals.
- Re-architected the bulk referral feature to handle 3–5x the original design load after organic usage outgrew initial capacity, turning it into a key retention lever for HR users.
- Built automated candidate profile extraction and Airtable-based daily calling list generation for the sourcing team, replacing manual list preparation.
- Built the full back end from scratch as a self-taught engineer, including Flask REST APIs, Google Drive API, and S3 integrations, and deployed it on Heroku.
Technologies: Node.js, Product Management, TypeScript, JavaScript, SQL, CRM, Chrome DevTools, Web Standards, Python, Express.js, Back-end Development, APIs, Databases, REST APIs, Web Application Architecture, MySQL
Product Management Intern
2021 - 2021
JSW Cement
- Served as a product management intern, driving digital adoption across dealer and sales operations at a major cement manufacturer (JSW Group).
- Reduced discount disbursement time by 90% through back-end automation of the approval and payout workflow.
- Designed real-time HR dashboards tracking the performance of 400+ sales officers across regions.
- Created a gamified dealer engagement framework with personalized nudges to reduce dealer churn, modeling a 48% reduction based on historical churn patterns.
- Built a construction cost calculator for the dealer-customer sales workflow.
Technologies: Product Management
Project History
021 Trade: SEBI-registered Stock Brokerage
Built a SEBI-registered stock brokerage from first commit as founding engineer, leading a 12-person team over 3 years.
Entire stack built in-house — OMS, KYC pipeline, market data via direct exchange leased line — with end-to-end order execution under 60ms.
The attached video shows a live trade: login, watchlist, market order on NSE, square-off, and confirmed P&L — real money, real execution, production infrastructure.
Entire stack built in-house — OMS, KYC pipeline, market data via direct exchange leased line — with end-to-end order execution under 60ms.
The attached video shows a live trade: login, watchlist, market order on NSE, square-off, and confirmed P&L — real money, real execution, production infrastructure.
Reddit Monitoring Tool
Built a Reddit monitoring tool that grew organically to 800 DAU and 1,500 MAU, handling 10,000 concurrent users when a viral post spiked traffic.
A distributed architecture of 6 collaborating bots manages Reddit's API rate limits, achieving 99.99% coverage of target posts and comments.
AI-powered relevance scoring and reply generation helped users surface and engage with the right conversations.
Built, marketed, and scaled — my best lesson in distribution: a solid product means nothing until people find it.
A distributed architecture of 6 collaborating bots manages Reddit's API rate limits, achieving 99.99% coverage of target posts and comments.
AI-powered relevance scoring and reply generation helped users surface and engage with the right conversations.
Built, marketed, and scaled — my best lesson in distribution: a solid product means nothing until people find it.
Sift: AI-powered Research-to-draft Chrome Extension
Chrome extension for turning web research into structured, referenced blog drafts — save snippets from any page, then generate drafts grounded in your saved material via a RAG pipeline (OpenAI embeddings, Qdrant vector DB) inside a Cursor-like editor. Built end-to-end solo: extension, back-end embedding/retrieval pipeline, and editor UI.
Education
2018 - 2022
Bachelor's Degree in Mechanical Engineering
IIT Bombay - Mumbai, India
Skills
Libraries/APIs
Node.js, React, Claude API, REST APIs, Zod, React Query
Tools
Claude, Claude Code, Zapier, n8n
Languages
Go, TypeScript, JavaScript, Python, SQL, Dart
Frameworks
Next.js, Express.js, JSON Web Tokens (JWT), OAuth 2, Tailwind CSS, Redux, Jest, Flutter
Paradigms
Microservices, Event-driven Architecture, Role-based Access Control (RBAC), Web Application Architecture, DevOps, ETL
Platforms
Docker, WordPress
Industry Expertise
Web Design
Storage
PostgreSQL, Data Pipelines, Databases, MySQL, Redis Cache, MongoDB
Other
WebSockets, Multi-tenant SaaS, Multi-tenant Architecture, Debugging, Back-end Development, Trading, Financial Markets, Fintech, Real-time Data, CRM, Chrome DevTools, Web Standards, Web Development, Full-stack, APIs, Cloud Architecture, API Integration, Dashboards, MVP Design, System Integration, Software Architecture, Vibe Coding, Consulting, Training, Front-end Development, Technical Writing, Real-time Data Pipelines, Integration, Large Language Models (LLMs), Workflow Automation, Workflow Automation & System Integration, SaaS, Software as a Service (SaaS), Performance, Supabase, Full-stack Development, AI Integration, Front-end, Responsive Web Apps, SSG, Server-side Rendering (SSR), LLM Agents, AI-assisted Development, AI-generated Code, Integrations, AI Automation, Low-latency Software, Concurrency Patterns, Multithreading, Code Review, Cross-browser Compatibility, Agentic AI, Artificial Intelligence (AI), Technical Leadership, Distributed Systems, Application State Management, Responsive UI, User Experience (UX), User Interface (UI), Finance, Privacy, Security, AI Agents, ETL Pipelines, Product Management, Retrieval-augmented Generation (RAG), RAG Pipelines, Qdrant, Chrome Extensions, ETL for AI
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