From Trainee to Senior Software Engineer: Sandaruwan Jayasundara's Career Path and Lessons
Trainee, associate, software engineer, senior — four roles at three companies. Here is the path as it actually happened, and the advice I'd give to engineers earlier in theirs.
I'm Sandaruwan Jayasundara, a Senior Software Engineer at Decryptogen LLC, a US company I work with remotely from Sri Lanka. I started as a Trainee Software Engineer at Wenthura Solutions in November 2021, moved to Associate Software Engineer there, then joined Mobitel as a Software Engineer in April 2023, and became a Senior Software Engineer at Decryptogen in July 2024. Along the way I completed a BSc (Hons) in Information Technology, specialising in Software Engineering, at SLIIT.
Key takeaways
- The path: NIBM (2017–2018) → SLIIT (2019–2023) → Wenthura Solutions (2021–2023) → Mobitel (2023–2024) → Decryptogen LLC (2024–present).
- Each move widened scope: from contributing to features, to enterprise systems, to leading the design of full applications and AI systems.
- Working on both frontend and backend early made later full-stack and architecture work much easier.
- Certifications were most useful when paired with real projects — cloud and AI in particular.
- Seniority is about ownership and judgement, not a job title or a number of years.
Education: the foundation
My formal path into software started at the National Institute of Business Management (NIBM), where I completed a Certified in Computer Software Engineering programme in computer science between 2017 and 2018. I then studied for a BSc (Hons) in Information Technology, specialising in Software Engineering, at the Sri Lanka Institute of Information Technology (SLIIT) from 2019 to 2023.
The degree overlapped with the start of my working life: I joined Wenthura Solutions as a trainee in late 2021, while still at SLIIT. The full details are on my education page.
Wenthura Solutions: trainee to associate (2021–2023)
Trainee Software Engineer — Nov 2021 to Jun 2022
I started at Wenthura Solutions in Colombo as an intern and progressed to contributing to both frontend and backend applications. This was where I learned Java, Express.js and Node.js in a professional setting, alongside the workflows that university doesn't fully teach: code review, version control in a team, and shipping to a real deadline. The work centred on web application development with React, Node.js and MongoDB.
Associate Software Engineer — Jun 2022 to Mar 2023
As an Associate Software Engineer I was part of the R&D development team, again working across frontend and backend. I designed and developed healthcare-focused platforms, including a medical software project for clients based in Sweden. Healthcare software raises the bar on correctness and data handling, and working for clients in another country was my first experience of collaborating across time zones.
Mobitel: enterprise and telecom scale (2023–2024)
In April 2023 I joined Mobitel (PVT) LTD in Colombo as a Software Engineer. The focus was full-stack development of large-scale enterprise and telecommunications applications with Java, Spring Boot, Apache Kafka, React.js, TypeScript and Angular, on SQL databases including Oracle DB and Informix DB, with Jenkins, Docker and deployments on Microsoft Azure.
Projects I worked on there included:
- A reporting system — data analytics and reporting dashboards
- The Mobitel mConnect web application
- The Mobitel Inventory Management System
- The Mobitel Upahara Package Management System
- An automated SMS delivery platform for new SIM card purchases and network activations
- Internal tools and API development
Enterprise telecom work teaches a different discipline from startup work: established databases, integration with existing systems, event streaming with Kafka, and changes that have to fit carefully into a large estate. It is also where Java and Spring Boot became one of my core strengths, which I now offer as Java and Spring Boot development.
Decryptogen LLC: senior engineer and AI (2024–present)
Since July 2024 I've been a Senior Software Engineer at Decryptogen LLC, a United States company, working full-time and remotely. My role is leading the design and development of modern, scalable web applications with React, Next.js, React SSR, Spring Boot, Node.js and Python; DevOps with Docker and Jenkins; deploying on AWS; and working with both MongoDB and PostgreSQL. A growing part of the work is AI development with OpenAI, LangChain and FAISS, collaborating with international teams.
Projects in this role include:
- Aiden — an AI chat assistance application built as a RAG-based intelligent chat system
- Audience Craft AI — an end-to-end text-to-SQL AI system (see the Audience Craft case study)
- An HR management system covering the full employee lifecycle
- A centralised admin portal and management dashboard
- A website revamp with a modern Next.js redesign
You can see these and other work on my projects page, and the full role history on my experience page.
Certifications along the way
I've used certifications to add structure when moving into a new area. In rough chronological order:
| Year | Certification | Issuer |
|---|---|---|
| 2021 | Introduction to JavaScript DOM Page Elements | Alison |
| 2021 | Introduction to Angular | Microsoft |
| 2022 | Convolutional Neural Networks | Coursera / DeepLearning.AI |
| 2022 | Computer Vision Mobile Applications | CV Zone |
| 2022 | Foundations of User Experience (UX) Design | |
| 2023 | ChatGPT Prompt Engineering for Developers | DeepLearning.AI |
| 2023 | LangChain for LLM Application Development | DeepLearning.AI |
| 2023 | AWS Cloud Essentials; AWS for Games | Amazon Web Services |
| 2025 | AWS Certified Cloud Practitioner | Amazon Web Services |
Credentials and verification links are on my certificates page.
Lessons for engineers earlier in the path
These are general lessons, framed as advice. They're what I'd tell a graduate starting their first role today.
1. Don't specialise too early
Working on both frontend and backend in your first roles builds a mental model of the whole request path — browser, API, database, deployment. That model is what lets you make good architecture decisions later. Specialise once you know what you're choosing between. The full-stack developer roadmap lays out a sensible order for learning it.
2. Learn the boring fundamentals deeply
Frameworks change; SQL, HTTP, data modelling, concurrency, and reading other people's code don't. Engineers who understand fundamentals pick up new stacks quickly — moving between React, Angular, Spring Boot and Node.js is far easier when you understand what each is abstracting.
3. Different environments teach different skills
R&D teams, large enterprises and international product companies reward different things: speed of exploration, careful integration, and end-to-end ownership. Spending time in more than one kind of environment makes you more adaptable than repeating the same year several times.
4. Seniority is scope, not syntax
The jump to senior is less about writing cleverer code and more about owning outcomes: clarifying requirements, choosing trade-offs, unblocking others, thinking about operations and cost, and leaving systems easier to change. Writing clear code is part of that — see clean code principles for modern developers.
5. Pair learning with shipping
Courses and certifications give structure; projects give understanding. When you study a topic — cloud, LLMs, computer vision — build something with it soon afterwards, even something small.
6. Communication is a technical skill
Remote, cross-time-zone work runs on writing: clear pull request descriptions, design notes, status updates and questions that can be answered asynchronously. Invest in it as deliberately as you invest in a new framework.
FAQ
Who is Sandaruwan Jayasundara?
Sandaruwan Jayasundara is a Senior Software Engineer based in Sri Lanka, working at Decryptogen LLC (United States) since July 2024. He works across React, Next.js, Node.js, Spring Boot and Python, deploys on AWS, and builds AI applications with OpenAI, LangChain and FAISS.
Where did Sandaruwan Jayasundara study?
He holds a BSc (Hons) in Information Technology specialising in Software Engineering from the Sri Lanka Institute of Information Technology (SLIIT), studied from 2019 to 2023, and earlier completed a Certified in Computer Software Engineering programme at the National Institute of Business Management (NIBM) in 2017 to 2018.
Which companies has Sandaruwan Jayasundara worked for?
Wenthura Solutions in Colombo as Trainee Software Engineer (Nov 2021 to Jun 2022) and Associate Software Engineer (Jun 2022 to Mar 2023), Mobitel (PVT) LTD in Colombo as Software Engineer (Apr 2023 to Jul 2024), and Decryptogen LLC as Senior Software Engineer (Jul 2024 to present).
How long does it take to become a senior software engineer?
There is no fixed timeline. Seniority is about scope and judgement: owning features end to end, making sound technical trade-offs, and raising the quality of the team's work. Breadth of real production experience usually matters more than the number of years.
Are certifications worth it for software engineers?
They are worth it as structured learning and as a signal when moving into a new area such as cloud or AI, but they do not replace shipped work. The most useful approach is to pair a certification with a project where you apply what it covers.
Get in touch
More about me is on the about page. If you'd like to work together or just compare notes on engineering careers, send me a message.