KofiFrimpong

Engineer on Polaris, a multi-tenant platform serving 9 products from 33 shared domain modules — NestJS and gRPC microservices, a Kafka event bus, PostgreSQL with schema-per-service isolation, SpiceDB access control, and React micro-frontends composed via Module Federation. Also on dedicated product teams for fintech and events clients.

• Built the G-Money financial-services admin console end to end — the operational tool for 8,200+ mobile-money customers (98.5% active, ~774 new per month): customer management, transaction monitoring, RBAC, audit logging, feature flags, CSV/PDF export.
• Own production reliability across the platform: OpenTelemetry distributed tracing over 15+ microservices, a transaction-error indexing pipeline into OpenSearch with Grafana dashboards, and Loki structured logging with sensitive-data masking on financial paths.
• Migrated the audit-log subsystem from PostgreSQL to OpenSearch, and added admin session management with suspicious-activity detection.
• Shipped two complete frontends for Xplora in under four weeks — an organiser dashboard and an 18-phase consumer events app (feed, stories, ticketing, live voting, social matching) — alongside backend work on promotions, QR door check-in, and Paystack payments.
• Delivered 7 modules of a supermarket POS/PWA, documented 30+ platform defects with reproductions, then fixed them in the shared platform. Built the GitHub App integration for Opero with webhook validation and PR-to-task linking.

• NestJS
• gRPC
• Kafka
• PostgreSQL
• SpiceDB
• Redis
• React
• Module Federation
• OpenTelemetry
• OpenSearch

• G-Money ↗ — company site — the admin console I built is internal
• Polaris — internal platform — powers every product we ship

Co-founded MySapienta and own its technical direction as CTO — a 7-application school-management platform built with Express, Drizzle ORM, PostgreSQL, Redis, and BullMQ in a Turborepo monorepo. ~89,700 lines contributed to the backend API, plus two frontends owned end to end.

• Rewrote the timetable generation engine as a bounded backtracking constraint solver — 1.5-second wall-clock deadline checked on a bitmask interval, viability pre-check, per-class double-block budgeting, and graceful degradation to greedy placement — shipped with a dedicated stress-test harness.
• Built WhatsApp notification infrastructure from scratch: provider layer, template management, and WhatsApp-first routing with silent automatic SMS fallback, so delivery never fails visibly to a school.
• Built the student and guardian portals end to end — grades with continuous assessment, attendance heatmaps, multi-ward switching, fees and receipts, PDF term reports, and 2FA OTP sign-in.
• Shipped student check-in/check-out with a verified-collector flow ensuring a child is released only to an authorised adult, and made every app an installable PWA with background auto-update.

• Express
• Drizzle ORM
• PostgreSQL
• Redis
• BullMQ
• Next.js
• Turborepo

• mysapienta.com ↗

Engineer across three products for a New Zealand-based studio, working remotely from Accra. Principally Spok, a venture-capital fund-management platform where I was top contributor on both repositories, leading the AI and retrieval workstream. Built on NestJS and Nx, PostgreSQL and Prisma, React and Vite.

• Built an AI email agent ingesting investment email over a persistent, health-monitored IMAP connection, using GPT-4o to extract companies, founders, valuations, and round terms into structured records with confidence scoring, semantic company matching, and duplicate prevention.
• Implemented three complementary retrieval systems: Pinecone semantic search with live index synchronisation, LlamaIndex company-scoped RAG returning document and section citations, and Gemini File Search with rate limiting.
• Built a mark-to-market valuation engine with multi-currency conversion driven by a scheduled Wise exchange-rate job, and shipped an AI reporting suite with Excel/PDF export and conversational regeneration with inline editing.
• Executed a full Firebase-to-PostgreSQL migration including file relocation to object storage, and ended recurring production deploy failures by making the entire Prisma migration chain idempotent.
• On Pactify.ai, an AI-assisted IP-licensing platform: agreement drafting, recurring-event scheduling, and real-time calendar sync with external providers — React, TypeScript, Firebase, Stripe, and a Python service layer.
• On Purposely.ai, an AI ad-generation platform for marketers: a GraphQL monorepo with Relay and Prisma on AWS, where keeping schema in sync between backend and frontend was the central engineering problem.

• NestJS
• Nx
• Prisma
• PostgreSQL
• OpenAI GPT-4o
• Google Gemini
• Pinecone
• LlamaIndex
• React
• GraphQL
• Firebase
• Stripe

• app.spok.vc ↗ — clients onboarded directly
• pactifyai.com ↗
• purposely.ai ↗

Lead engineer on the client application across two products over three years, authoring ~80% of commits on the main repository and setting the testing and release standards the team worked to. The platform has processed 5,600+ responses across 675+ live interactive sessions.

• Built five product surfaces end to end, each from empty state to production: Quick Polls, Anonymous Q&A, Surveys, Quizzes, and real-time multiplayer Trivia.
• Engineered real-time multiplayer Trivia over WebSockets: room join and reconnect, countdown timers synchronised across page refresh, mid-game join with full state resync, session-token rotation, and automatic recovery that removed the manual retry path entirely.
• Designed and shipped Jam Sessions, a live presenter mode enforcing a single-running-tool invariant, with QR join overlays, host-to-presentation mirroring via BroadcastChannel, and resilient reconnection with state recovery.
• Built a survey engine with 8+ question types, conditional branching, IndexedDB draft persistence, a three-tier authentication fallback chain, and CSV/ZIP export, with subscription gating across every creation and submission flow.
• Established the Playwright E2E suite and CI pipeline, personally authoring the polls, survey, quiz, and Q&A suites within a 117-test harness.
• Patched CVE-2025-55182 (React2Shell), a critical CVSS 10.0 remote-code-execution vulnerability in React Server Components, via a Next.js 14 to 15 upgrade. Added Sentry instrumentation and full technical SEO.
• Earlier, as Votitude: built an election and awards voting platform with Paystack and MTN Mobile Money payments, CSV/XLSX voter-roll upload with duplicate detection, and live WebSocket vote tallies.

• Next.js
• TypeScript
• WebSockets
• Redux Toolkit
• IndexedDB
• Playwright
• Sentry
• Paystack

• jampolls.com ↗