Jonathan Ooi
Principal Software Engineer · Kuala Lumpur
I build and modernise the systems fintech runs on.
Payment platforms, bank integrations, high-volume settlement and reconciliation engines, and legacy modernisation. Designed, built, and shipped to production. Spec-driven, AI-assisted workflows shorten the path from business problem to working software.
Role
Principal Software Engineer @ Soft Space
Domain
Payments · Settlement · Reconciliation
Approach
Spec-driven, AI-assisted delivery
Engineering depth with business context.
Principal Software Engineer with experience across fintech, SaaS, consulting, and product engineering. I work where backend architecture meets product decisions, and I still write and ship code. My job is closing the gap between engineering, business, and product.
Recent work includes payment platforms, bank integrations, high-volume settlement and reconciliation systems, event-driven integration layers, and legacy modernisation done without stopping the business. I lead a team, manage stakeholders, and set the standards, specs, and the constitution AI follows, built on my boilerplate structure with OKF, RAG, skill creation, and context management.
High-volume backend and platform architecture for fintech
Payments, settlement, reconciliation, and bank integrations
Legacy modernisation and event-driven decoupling
Full-stack product delivery across React, Next.js, and mobile
Team leadership, mentoring, stakeholder management, and consulting
AI-assisted delivery: spec-driven development, OKF, RAG, skill creation, MCP, context management
Working experience.
Principal Software Engineer
Soft Space · Nov 2024 – Present
Focus: Backend architecture, fintech platform modernisation, system integration, and engineering delivery improvement.
- Built a reconciliation engine processing 10M+ transaction records per run, parsing, matching, and reporting in 10 minutes.
- Cut manual reconciliation and settlement from 5 hours to 15 minutes by rolling out automated services.
- Rolled out 20 new backend services to production, modernising legacy bottlenecks into scalable modules.
- Unified 4 separate system portals into one, reducing merchant onboarding time.
- Led and mentored 6 engineers, setting architecture direction across the platform's backend services and concurrent fintech initiatives.
- For well-specified feature work, an AI-assisted, spec-driven workflow turns multi-day tasks into same-day delivery, shifting effort to architecture, review, and testing.
Senior Full Stack Engineer
Paywatch · Jun 2023 – Oct 2024
Focus: Building the bank integration layer and platform services behind the company's expansion into new countries.
- Built the bank integration layer supporting 3 banks across 3 countries, replacing manual file-upload disbursement with a reusable regional foundation.
- Enabled near-instant disbursement, cutting the wait for withdrawn funds to reach a user's bank from around 4 hours to minutes on withdrawal.
- Cut new-market environment setup from 3 days to 1 hour by automating provisioning with Infrastructure as Code.
- Launched a bill payment integration supporting 50 billers and services, opening a new revenue stream.
- Built a rule engine turning business rules into customisable, visualised configurations across application services.
- Revamped customer portals with the product team and mentored engineers across the systems being built.
Senior Software Engineer
Pow Pocket Sdn Bhd · Apr 2022 – Jun 2023
Focus: Full-stack product delivery with TypeScript, React, and Next.js across healthcare and e-commerce systems.
- Delivered three production platforms across healthcare, pharmaceutical, and e-commerce within 14 months.
- Built an order management system taking a pharmaceutical company's ordering process online.
- Delivered an online doctor platform for rapid COVID testing.
- Developed a memorial plot management and agent commission distribution system.
- Built automated Cypress test flows validated against 50,000+ records, raising confidence in frontend releases.
- Integrated a healthcare app backend with an e-wallet provider and payment gateway.
From architecture decision to shipped system.
Backend & Platform Engineering
Backend systems, event-driven services, and API gateway layers designed for high-volume batch processing and operational load.
Legacy Modernisation
Breaking legacy bottlenecks into maintainable, modular systems without disrupting day-to-day operations.
Fintech & Bank Integrations
Payment, disbursement, settlement, and reconciliation layers across banks, vendors, and internal platforms, built middleware-first for multi-country expansion.
AI-Assisted Engineering
Spec-driven development with a constitution AI follows, built on my boilerplate structure: OKF, RAG, skill creation, MCP tooling, and context management that keep output consistent.
Full-Stack Product Delivery
Products taken from idea to production across backend, React and Next.js frontends, and mobile, from bidding platforms to healthcare and e-commerce systems.
Technical Leadership & Consulting
Leading teams, mentoring engineers, aligning stakeholders, and shaping proposals, architecture, and delivery from requirement to release.
Proof of work, not just a list of tools.
A few examples of the kind of business and technical problems I have worked on.
Legacy System Modernisation
Problem
Existing modules were tightly coupled, hard to scale, and difficult to maintain without disrupting business operations.
Solution
Decoupled key bottlenecks into standalone scalable services while maintaining backward compatibility with the existing ecosystem.
Impact
Improved maintainability, reduced operational dependency, and created a cleaner foundation for future expansion.
Bank Integration Middleware
Problem
Manual file-upload disbursement created operational overhead and could not scale as the business expanded into new countries.
Solution
Initiated and built a middleware supporting 3 banks across 3 countries, provisioned through Infrastructure as Code.
Impact
Replaced manual disbursement with near-instant withdrawals, cutting user wait from around 4 hours to minutes, and new-market setup from 3 days to 1 hour.
High-Volume Reconciliation Engine
Problem
Manual reconciliation and settlement took around 5 hours per cycle, with large transaction datasets to parse, match, and report.
Solution
Designed a batch-processing workflow for reconciliation and reporting using cloud-native storage and processing patterns.
Impact
Processes 10M+ transaction records per run in 10 minutes, cutting manual reconciliation and settlement from 5 hours to 15 minutes.
AI Engineering Constitution & Workflow
Problem
AI-generated code drifted from existing architecture, folder structure, and shared engineering standards, and context was scattered across repos and people.
Solution
Set up a constitution for AI to follow, built on my boilerplate structure, combining spec-driven development, OKF knowledge bases, RAG, custom skill creation, and AI context management.
Impact
Turns well-specified multi-day tasks into same-day delivery, with output staying consistent with team standards across projects.
The tools behind the work.
Languages & Frameworks
Cloud & Infrastructure
Data & Storage
Architecture & Integration
AI-Assisted Engineering
Frontend & Mobile
Engineering discipline in the AI era.
Short essays and posts around software engineering, AI-assisted delivery, legacy modernisation, and senior engineering thinking.
Engineering fundamentals still matter in the AI era
Why understanding software engineering principles separates engineers who can judge AI output from those who accept it blindly.
Redefining the software engineer as AI writes the code
How engineers evolve into product thinkers who direct AI instead of competing with it.
Clear prompts beat perfect prompts
How detailed context upfront removes rounds of clarification when working with AI.
Spec-driven development with AI
How AI-assisted delivery shifts engineering effort from boilerplate to architecture, and months to weeks.