Lucknow, India · Est. 2021
Substring Technologies designs and ships web, mobile and cloud products for growing businesses. The same engineers run our classroom and online training programmes.
Tell us what you're building. We usually reply the same working day.
Alumni
Companies our graduates have joined after completing a programme with us.
Programmes
Live online and classroom training in full-stack development, taught by engineers who ship the same stack for clients.
Comprehensive program covering microservices design, containerization with Docker & Kubernetes, CI/CD automation, Terraform (IaC), and advanced AWS cloud architecture deployment.
Microservices · Docker · Kubernetes · AWS · +2
Cover core java revision, servlet, filters, spring framework, spring boot, generative ai, agentic ai, spring ai and 4 projects.
Java · Spring Boot · Generative AI · Spring AI
Learn HTML, CSS, React, Appwrite, Strapi & AI Integration and deployment by building 8 real-world projects.
HTML · CSS · React · Appwrite · +2
What we do
The work we ship for clients is the curriculum we teach. That is the whole idea behind how Substring is set up.
We take a product from requirement to running system — interface, API, database and deployment — and stay on for the changes that follow launch.
For founders and business owners who need a working product, not a prototype.
Structured programmes in full-stack development, taught by engineers who are shipping the same stack for clients. Live classes, code review and interview preparation.
For students, working developers, colleges and corporate teams.
Work
A sample of what we have shipped — client products, internal tools and our own platforms.
A luxury bedding store selling Giza cotton sheets, hand-block dohars and sateen comforters. Built around collection filters and a rich catalogue, with a deliberately restrained storefront.
Next.js · React · Node.js · MongoDB
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An employee management system covering attendance, task assignment, activity logs and an admin control panel. Built for our own operations, then hardened for client use.
Next.js · React · Prisma · MySQL
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A local-first desktop app that downloads, catalogues and backs up Zoom cloud recordings to a local drive, so teams stop paying for cloud recording storage.
Electron · Node.js · Zoom API
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A platform for gym owners to run memberships, billing, class schedules and member progress from one dashboard, replacing spreadsheets and paper registers.
Next.js · React · Node.js
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An online store for spiritual products, with category browsing, user accounts and an integrated payment gateway through to checkout.
React · Express · MongoDB · Payments
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A responsive promotional site for a local gym covering facilities, trainers and membership plans, built to load quickly on mobile connections.
HTML5 · Tailwind CSS · JavaScript
(opens in a new tab)How we work
Same five stages on every engagement, whether it is a two-week build or a six-month platform.
A call to understand the problem, the users and the constraints you are working within — budget, timeline, existing systems.
We write down what will be built, in what order, and what it costs. You approve the scope before any code is written.
Interface and architecture in parallel, shipped in reviewable increments so you see working software early rather than at the end.
Testing, fixes from your feedback, then deployment to your cloud account with the pipeline and documentation handed over.
Post-launch changes, monitoring and fixes. You keep talking to the engineers who built it.
Why Substring
Five things we can point at, rather than five adjectives.
Our trainers write production code for client projects. Course material follows the decisions we actually make on delivery work — not a syllabus written once and left alone.
Learn Code With Durgesh has published over 1,300 free tutorials to an audience of 400,000+. The teaching is open, reviewable, and has been for years before you contact us.
Live online batches run nationwide, and our Lucknow centre runs classroom batches, college training and internships in person. You can visit us.
Small team, no account-manager layer. The person who scopes your project is one of the people who builds it, and answers when something breaks after launch.
We build on mainstream, well-supported stacks — Java and Spring Boot, React and Next.js, standard cloud tooling — so another team can pick it up without a rewrite.
Stack
We work in stacks with long support horizons and deep hiring pools, so your system stays maintainable after we hand it over.
Feedback
Comments left publicly on our courses and tutorials, quoted as written.
You are really doing a very good work for the upliftment of professionals and students like me. I cracked interviews in MNC after learning many things from your video only.
Excellent Spring Boot course! Durgesh sir's mentorship is top-notch. Concise, clear, and highly informative. A must for anyone looking to master Spring Boot quickly.
I can't express enough how transformative this React tutorial has been for me. It's engaging, thorough, and practical. Don't miss out on this opportunity to master React!
You are one of the best teachers sir. I really thought Docker is hard, but now after completing your Docker tutorial my concept is crystal clear.
Big fan sir. Aap ne mera future bana diya. Aapke course buy kar ke aaj bohot knowledge mili hai. Love from Gujarat.
Who we are
Substring Technologies started in 2021 as a way to give students access to industry-level programming material. The client work grew out of the teaching, and now the two feed each other.
Today we run summer training programmes in colleges, upskill corporate engineering teams, host internships and live classes on current technologies — alongside building and maintaining software for businesses.
Read our story
Durgesh Kumar Tiwari
Founder · Software engineer and educator
B.Tech, 2017. Left a role at an MNC in Bangalore to teach full-time, and has published free programming tutorials as Learn Code With Durgesh ever since.
Inside Substring
A short film from our Lucknow office and training floor.
Community
Years of tutorials, walkthroughs and Q&A, open to anyone. It is also the easiest way to judge how we teach before you pay for anything.
FAQ
If yours is not here, ask us directly — we answer the same day.
Yes. Most of our client work is delivered remotely across India, with calls scheduled around your working hours. Our office in Lucknow is open if you would rather meet in person.
With a call. We talk through the problem, the users and your constraints, then send a written scope with the work broken into stages and priced before anything is built.
You do. Work is delivered into your repository and deployed to your own cloud account, with the pipeline and documentation handed over at launch.
No. Our foundational programmes assume no prior knowledge and start from the basics. Advanced tracks in backend engineering and full-stack development expect some programming experience.
Both follow the same syllabus and projects. Classroom batches run at our Lucknow centre with in-person lab sessions; online batches are live and interactive, and every session is recorded for later access.
We run resume reviews, portfolio feedback, mock technical interviews and interview preparation, and refer candidates to companies hiring through our network. We do not guarantee a job offer.
Whether it is a product to ship or a team to train, start with a conversation. No form funnels, no sales sequence — you talk to an engineer.
