Jon McCallum

Lumberjack @ Posthog

United Kingdom

About

Product Engineer

Experience

  • Product Engineer at PostHog
    Nov 2025 - Present · 8 mos

    Shipping the observability trinity - Logs, Metrics & Traces

  • Founder at KitNDocs
    Jul 2023 - Present · 3 yrs

    Founded and scaled a B2B/B2C SaaS platform used by 100+ skydivers internationally Architected robust backend with TypeScript, Node.js, and PostgreSQL Launched companion mobile app with NFC tagging and offline capabilities Featured speaker at the 2024 UK Skydiving Expo; recognised in British Skydiving Magazine

  • Full Stack Engineer at State of Play Hospitality
    Feb 2024 - Nov 2025 · 1 yr 10 mos

    • Achieved 5–15% improvements in conversion rates through UX enhancements by leading testing initiatives from conception to implementation and review, including developing features for an internal A/B testing platform and conducting thorough usability tests using tools like Hotjar. • Managed five high-traffic websites for international brands, built with React.js and Next.js featuring headless WordPress backends, ensuring optimal performance and user satisfaction. • Designed and implemented scalable backend systems using NestJS, TypeScript, and TypeORM, applying SOLID and object-oriented programming principles with SQL databases like MySQL and PostgreSQL. • Streamlined CI/CD pipelines by implementing DevOps practices with GitHub Actions, boosting deployment efficiency and reliability. • Implemented test-driven development practices, using Jest for unit tests and Cypress for integration tests, ensuring high code quality and robust user flows. • Alchemised data into design and design into code by creating designs in Figma and transforming them into functional UIs using React, Next.js, React Native, and Vue.js. Designed booking funnels and user flows from wireframe to completion, optimising user experience through data-driven decisions. • Led rapid design and development cycles, emphasising swift iterations and prompt delivery to test and validate prototypes. This approach ensured products exceeded user expectations while aligning with business Objective Key Results (OKRs) and Key Performance Indicators (KPIs). • Collaborated closely with multiple departments—including marketing, sales, and finance—across global time zones, providing support and problem-solving that drove business objectives forward. • Developed Node.js scripts to process data from SQL and NoSQL databases, including deploying solutions on on-site hardware to remotely collect data from ping pong tables, enhancing business intelligence capabilities.

  • ParaCode (Full-time · 1 yr 9 mos)
    • Full Stack Developer
      Dec 2022 - Jan 2024 · 1 yr 2 mos

      As a .NET Developer at Paracode, a cutting-edge insurance platform shaping the future of the insurance sector, my responsibilities included: • Collaborated in the development and maintenance of the Paracode insurance platform using .NET Core, ensuring software solutions aligned with company goals and enhanced user experience. • Utilised MVC, Entity Framework, and LINQ to guarantee efficient performance and robust security. • Actively engaged in all phases of the software development life cycle, ensuring tasks were executed timely and to a high standard. • Continuously integrated best practices and kept abreast of evolving trends and technologies in the .NET ecosystem. • Worked closely with cross-functional teams to ensure software solutions met user needs and business objectives. • Contributed to the ambitious mission of Paracode, being part of a team innovating the insurance industry.

    • Full Stack Developer
      May 2022 - Dec 2022 · 8 mos

      At KLOC Digital Solutions (now Paracode), as a full-stack web developer, I played a pivotal role in various client projects: • Spearheaded the integration of Stripe into Cote Brasserie's Vue3 booking system, enhancing payment processing capabilities. • Optimised the reservation system using Vue3, improving user efficiency and streamlining the booking process. • Designed custom APIs to enhance interactions with third-party systems, including CRMs and table management ePOS systems. • Leveraged PHP and WordPress expertise to deliver tailored solutions on both legacy and new development projects. • Maintained a steadfast commitment to quality, timelines, and client satisfaction, ensuring projects met or exceeded client expectations. • Collaborated closely with clients and internal teams, fostering strong relationships and clear communication.

  • Freelance WordPress Developer & Designer at Jamdd
    May 2019 - Dec 2023 · 4 yrs 8 mos

    • Designed and developed WordPress websites for multiple clients, ensuring they were both functional and visually appealing • Created custom logos and branding for client websites, enhancing their online identity • Designed website layouts and user interfaces, focusing on clean, user-friendly designs • Edited and managed website content, ensuring clarity and alignment with client goals • Integrated and configured plugins to extend site functionality • Provided ongoing website maintenance, updates, and troubleshooting to keep sites running smoothly • Worked across multiple client projects simultaneously, delivering solutions that met both technical and aesthetic requirements