Ejeh Daniel

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Ejeh Daniel

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Professional summary

Hi, I'm Daniel, a Senior Frontend Engineer. I spend most of my time building fast production web apps, custom browser tools, and AI features. I've worked as part of founding teams and took products to launch from early MVPs. My stack is React, TypeScript, and Node.js, with a strong focus on testing, maintainable architecture, accessibility, and good UX.

At Doow, I've built core product features spanning web apps, browser extensions, and desktop agents including our AI CFO interfaces (built a 60 FPS spreadsheet from scratch that runs 100k+ cells with a custom formula compiler), and our internal AI review agent that saves the engineering team ~1,000 hours a week.

I'm comfortable owning frontend infrastructure, mentoring engineers, and working across product and engineering. Outside of work, I build audio and browser automation tools in Python and Rust.

Professional experience

Senior Frontend Engineer

Doow — Wilmington, Delaware, United States · Remote

May 2025 – Present

  • Built Doow's cardholder and card-management experience on the web, integrating card issuance, transactions and lifecycle management across onboarding, spend controls and approval experiences with role-aware access controls.
  • Built the frontend for Doow's AI CFO agents from the ground up, owning the streaming generative UI that powered agent responses, actions, interactive experiences, and human approvals across the product.
  • Built Doow's native spreadsheet engine for its AI CFO agents from scratch, supporting 100,000+ cells at 60 FPS with custom grid rendering and virtual scrolling, cutting frame times during intensive scrolling by 85% and CPU-to-GPU transfer latency by 70%.
  • Built the spreadsheet calculation engine around a custom formula compiler, dependency graph and background workers, eliminating UI-thread blocking for complex spreadsheet calculations.
  • Substantially added deterministic formula evaluation and XLSX interoperability into the spreadsheet engine, defining explicit precision and compatibility policies and validating behavior against a multi-thousand-case formula corpus and XLSX round-trip test suite.
  • Architected and expanded Doow's SaaS usage tracking system, including browser and desktop agents end-to-end, processing 30M+ activity events across 4,500+ applications, increasing user adoption by 15%, and enabling finance and procurement teams to identify
  • Implemented automated test suites and CI/CD pipelines for Doow's browser extension and desktop agent, covering unit, component, and end-to-end testing with Vitest and Playwright, enabling <45-minute merge-to-release delivery and automating 30+ releases.
  • Contributed in building Hawky, Doow's internal AI code-review system, reviewing 80% of 25K weekly code diffs with 70% of comments marked useful and 60% addressed in a 5-minute median, using repository-aware sub-agents and automated quality filtering to save ~1,000 developer hours weekly.
  • Architected and owned Doow's frontend performance and reliability system, combining real-user and synthetic monitoring to catch production regressions and improve Core Web Vitals, with benchmark results of LCP 3.26s → 1.78s and CLS 0.41 → <0.10, while using the Doow Reliability Score to track route-level health and SLOs.
  • Integrated and setup the product analytics and usage intelligence system to track how users and organizations use the product, turning product events into adoption, funnel and conversion insights, with benchmark outcomes of, 30% higher conversion and $1M+ ACV.
  • Improved application performance by reducing initial load time by 3.5s and bundle size by 52% through advanced code-splitting, lazy loading, and webpack optimization
  • Built a responsive procurement and spend insights dashboard, and needs-attention board, improving user task completion rates for crucial things that need attention by 35%.

Frontend Engineer

Doow — Wilmington, Delaware, United States · Remote

October 2024 – April 2025

  • Worked on shared frontend systems and component libraries for Doow's web product, establishing team-wide standards and reusable patterns for data fetching, prefetching, optimistic updates, and responsive interfaces to mask network latency and consistently deliver sub-second interface feedback.
  • Led comprehensive accessibility audits and clean-up sprints, implementing semantic HTML, focus-visible states, and WCAG-compliant color contrast to achieve 100% compliance across core financial dashboards.
  • Built and owned the documentation infrastructure, while contributing to the product surfaces across the landing page to increase user conversion by 15%, and working closely with the founding team as new product features took shape.
  • Ideated and built a browser extension, taking it from the initial product work through production across Chrome, Firefox, and Safari stores. connecting application activity to Doow's backend and product.

Frontend Engineer

Hexelan Consulting Ltd — Abuja, Nigeria

July 2022 – January 2023

  • Worked on and maintained a real-time Vue.js dashboard for an enterprise data collection system used to securely capture high-stakes election field data from thousands of remote agents.
  • Designed a live, low-latency reporting layer using Vue.js, Socket.io, and D3.js to dynamically update stakeholder dashboards with incoming data streams while preventing main-thread performance degradation.
  • Structured application global state and modular layouts using Pinia, keeping massive real-time data flows manageable and highly performant on low-end mobile devices and constrained mobile networks.

Selected projects

REAPER MCP

Python · Lua · MCP · REST

Built a Python-based Model Context Protocol (MCP) server that exposes a 170-operation REST API to REAPER via a Lua bridge, allowing an AI assistant to arrange, mix, and render audio tracks with a one-step undo system.

StemSplitter

React · FastAPI · PostgreSQL · Redis · Modal

Developed a React web app that splits songs into eight isolated tracks. Integrates a FastAPI backend that orchestrates GPU-accelerated separation models on Modal, using Redis/RQ for job queues and PostgreSQL for state.

Peruz

TypeScript · Node.js · Chrome Native Messaging · MCP

Built a headless browser automation tool in Node.js connected to a Chrome Extension via Native Messaging. Exposes browser states, network requests, and viewport screenshots to terminal prompts and MCP clients.

Education

Bachelor of Engineering, Agricultural and Bio-systems Engineering

Joseph Sarwuan Tarka University, Makurdi

Technical skills

Languages: TypeScript, JavaScript, Python, Rust, SQL, HTML5, CSS3

Frontend: React, Next.js, Vue.js, Vite, Tailwind CSS, Shadcn UI, Radix UI, D3.js, Web Accessibility (WCAG 2.1)

Backend and data: Node.js, FastAPI, PostgreSQL, Redis, REST APIs, GraphQL

AI and tooling: AI SDK, RAG Systems, OpenAI API, LangChain

Tools and DevOps: Playwright, Vitest, Docker, GitHub Actions, Turborepo, Core Web Vitals