About Jeshurun

A senior fullstack engineer building agentic systems.

I'm Jeshurun — a senior fullstack engineer based in Finland, with seven years building production software for teams from London to Washington. I currently lead AI-feature work at SingleFile, a SaaS platform serving over 130,000 companies, where I shipped the CTA flow that helped close a $9M funding round.

Outside that work I build agentic systems. careerscv.io is mine — an AI platform with 500+ users that wires 8+ LangChain agents over Claude and OpenAI through MCP servers, plus a voice assistant for hands-free CV editing. My MSc thesis at Tampere University was on designing those kinds of systems at scale.

The skills behind it: React, Next.js, TypeScript, Django, GraphQL on one side; LangChain, MCP, Claude and OpenAI APIs on the other; Jest, Cypress, Playwright keeping it all honest. I care about systems that are fast, well-tested, and pleasant to use — and about teaching the next engineer behind me how to keep them that way.

What I work with

The tools, ranked by how often I reach for them.

AI · Agents

● Specialism
LangChainMCP ServersAnthropic Claude APIOpenAI APIGrok APIGoogle Generative AIAgentic Systems

Frontend

ReactNext.jsTypeScriptJavaScriptTailwind CSSReact QueryRedux

Backend

Node.jsDjangoGraphQLREST APIsPostgreSQLMongoDB

Testing

JestCypressPlaywright

Platform

AWS (EC2, Lambda, RDS, S3)DockerGitHub ActionsViteWebpack
Experience

Seven years of shipping.

  1. Apr 2022 — Present
    Full-time

    Senior Software Developer

    SingleFile Inc · Washington, USA

    • ●Lead AI-feature work on an enterprise SaaS platform serving 130,000+ companies.
    • ●Delivered the CTA project that contributed to the company securing a $9M funding round.
    • ●Built 50+ reusable React/TypeScript components with Jest + Playwright coverage.
    • ●Cut API response time by 35% through Django REST optimisation.
    • ●Mentored 2 junior developers in React architecture, testing and code quality.
    ReactTypeScriptDjangoJestPlaywrightGraphQLNode.js
  2. May 2020 — Oct 2021
    Full-time

    Founding Frontend Developer

    Happierleads · London, United Kingdom

    • ●Architected the frontend codebase and component patterns from zero — became the team standard.
    • ●Designed a Storybook-driven library of 40+ React/TS components.
    • ●Reached 88% coverage (Jest + Cypress); halved the bug-escape rate.
    • ●Cut bundle size 30%, lifted Core Web Vitals, +25% engagement.
    • ●Shipped 8+ user-facing features, +35% feature adoption.
    ReactTypeScriptJestCypressStorybookNode.js
  3. Mar 2020 — May 2020
    Contract

    Frontend Developer (Contract)

    GG Software Ltd · United Kingdom

    • ●Built and maintained React/TS components for gameanalytics.com — 50M+ daily events.
    • ●Reached 85% coverage with Jest + Cypress in a 3-month window.
    • ●Resolved 40+ complex component issues; cut page load 25%.
    ReactTypeScriptCypressJestREST APIs
  4. May 2013 — Nov 2013
    Internship

    Software Intern

    Amitech Computers · Anambra, Nigeria

    • ●Built responsive pages and e-commerce features with HTML, CSS, PHP, JavaScript.
    • ●Shipped auth, form validation and payment integration modules.
    • ●Optimised queries — −20% page load.
    HTMLCSSPHPJavaScript
Education

Two degrees, one obsession — agentic systems.

The thesis sets the lane: an MSc dissertation on designing scalable agentic systems with LLMs, built on a foundation in computer engineering.

  1. 01
    Aug 2022 — Dec 2024

    MSc, Computer Science

    Tampere University

    Tampere, Finland

    Thesis: Designing Scalable Agentic Systems with LLMs

  2. 02
    Aug 2010 — Aug 2015

    B.Engr, Computer Engineering (Hons)

    Federal University of Technology, Minna

    Nigeria

Open for new work

Let's build something that ships.

I'm taking on one new project at a time. If you're shipping product — especially anything agentic, AI-native or genuinely hard — I'd like to hear about it.

Start a conversation

Or email jeshurunnonso@gmail.com