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John Adekoya

Building the software money moves through.

Full-Stack Engineer at Stransact (RSM International).
I turn payroll, payments and tax rules into systems people can trust.

Five years across iPaySuite, GridCore, NRS Compliance and TimeX. BSc Accounting.

Explore my work

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Selected work

Financial platforms, owned from schema to screen.

GridCore

Lead engineer · Go, PostgreSQL, React

2026 rewrite

Rewriting a payments platform in Go, ledger first.

I led the ground-up Go rewrite of a prepaid-electricity payments platform: fourteen bounded contexts, a double-entry ledger, hardware token vending, and a four-app React monorepo.

94k lines

of Go across 14 bounded contexts, with a double-entry ledger whose trial balance is a standing test

499 tests · 160+ API operations

Visit gridcoreinc.com

iPaySuite

Full-stack engineer · Laravel, React, MySQL

Payroll, invoicing and payouts for ₦2.1 billion a month.

I built the invoicing and bulk-payout modules from schema to screen for a payroll suite that moves ₦2.1 billion a month across about twenty corporate clients.

₦2.1B+

processed in payroll every month for around 20 corporate clients

₦20M+ weekly maker-checker payouts

Visit ipaysuite.com

  • 01 RSA/SHA-256 signing · deterministic canonical payload
  • 02 IRN generation · QR encryption to the FIRS spec
  • 03 drivers: direct API · SmartVAT · in-house gateway
  • 04 Xero · Zoho Books · QuickBooks via OAuth2 + HMAC webhooks
  • 05 idempotency keys · append-only audit ledger
  • 06 exponential-backoff retries · forward-only status transitions
  • 07 81 tests · 14 property-based suites

NRS Compliance

Founding engineer · Laravel, React, PostgreSQL

Compliance infrastructure for Nigeria's e-invoicing mandate.

I founded and architected the access-point platform that signs, encrypts and submits invoices to the tax authority, with three pluggable drivers and Xero, Zoho and QuickBooks integrations.

14 suites

of property-based tests over signing, encryption and idempotency, in a codebase I authored solo

81 tests · 3 submission drivers

Production, private

TimeX

Lead frontend · Laravel, Inertia, React

Three years as the #1 frontend contributor.

Three years as lead frontend and repo maintainer: leave, attendance and timesheets built full stack, plus a Feature-Sliced migration with lint-enforced boundaries.

583 commits

about 52% of the surviving frontend, three times the next contributor

130+ pull requests merged as maintainer

Visit timex.stransact.net

Also shipped

Smaller builds and a side project.

Native, too

Two apps,
built in SwiftUI.

The same care for data and state, on a phone. Shipped as native iOS apps, not wrappers.

  • TimeXP

    iOS · Business · App Store

    Clock-in, timesheets, leave and expense claims for teams, with approvals built in.

  •

    iPaySuite

    iOS · Finance · App Store

    Payslips, pay history and a PAYE tax estimator for employees on iPaySuite payroll.

Engineer at work. Accountant by training.

Lagos roots.
A finance route.

I’m John. I studied accounting, then spent five years building the software that runs payroll, invoicing, tax filings and prepaid electricity for Nigerian businesses. The degree is not decorative: I understand the ledger I am writing to.

I own features from the database schema and the API contract to the React screen, and I like boundaries you can lint, tests that pin down invariants, and numbers that reconcile to the kobo.

Frontend
React, TypeScript, Next.js, Astro, Inertia, Tailwind, shadcn/ui, TanStack Query, Storybook
Mobile
SwiftUI, iOS
Backend
Go (chi, GORM, River), Laravel, NestJS, REST and OpenAPI, OAuth2, BullMQ
Data
PostgreSQL, MySQL, schema design, double-entry ledgers
Fintech
E-invoicing and RSA signing, Paystack, Monnify, multi-currency, withholding tax, maker-checker, STS vending
Quality
Pest, Go integration tests, property-based testing, Vitest, RTL, Sentry, GitHub Actions

BSc Accounting, University of Ilorin, 2021

MSc Information Technology, Miva Open University, expected 2026

The longer version

Portrait of John Adekoya

My route here

  1. One Purse Inc.

    Frontend Engineer

    2022

  2. Fountain of Hope

    Frontend Engineer, volunteer

    2022 — now

  3. Stransact

    Full-Stack Engineer

    2022 — now

RSM International, Lagos. Lead engineer across iPaySuite, NRS Compliance, TimeX and GridCore; 130+ PRs merged as maintainer.

Say hello

Let's build something that moves money safely.

Open to senior frontend and full-stack roles, remote or Lagos. Replies within a day on weekdays.

Email me