Julian Tellez

The largest commercial television network in the UK, broadcasting and streaming news, entertainment, drama and live events via ITVX.

• Engineered playback splitting to serve optimised players by device capability, cutting bundle size from 1MB to 300KB gzip and improving load times.
• Built ad-block detection and deterrence, protecting and increasing advertising revenue.
• Contributed to the migration from Shaka Player to TheoPlayer, improving playback performance and features.
• Prepared the platform for high-traffic live events including the World Cup, ensuring stable streaming.

Shaka Player, TheoPlayer, hls.js, MPEG-DASH, HLS, TypeScript, React, Webpack, Jest, Cypress

A provider of secure digital video delivery: multi-DRM licensing, cross-platform player SDKs and content protection.

• Prototyped Server-Guided Ad Insertion (SGAI) for DASH (DASH-XLink) and HLS (EXT-X-DATERANGE interstitials), evaluating cross-platform compatibility for live and VOD.
• Explored hybrid ad-insertion architectures to inform future monetisation and seamless user experience.

castLabs Player, MPEG-DASH with DASH-XLink, Apple HLS interstitials, TypeScript, React, Webpack, Jest

A leading British broadcaster and telecommunications company.

• Developed Adaptive Bitrate Streaming (ABR) algorithms, improving playback quality and reducing buffering.
• Enhanced bandwidth estimation and request efficiency, reducing time to first byte and playback latency.
• Implemented buffer-management strategies to improve streaming across Chromium browsers.

React + Hooks, TypeScript, vanilla JS, Webpack, Sass, Selenium, Node.js (Express)

A multi-service provider bundling home services into one bill.

• Engineered real-time communication and payment services handling 1M+ daily events via Kafka and Kubernetes, improving system throughput and observability using Prometheus and Grafana.
• Leveraged cloud-native technologies (Kubernetes, Docker, Kafka) for scalable, resilient architectures.
• Ran proactive monitoring and resolution with Prometheus and Grafana.

React + Hooks, GraphQL, TypeScript, Kubernetes, Docker, Kafka, Terraform, Go, CircleCI, GitHub Actions, Drone, AWS, GCP

A leading live and on-demand sports streaming service.

• Optimised HTML5 video playback across Xbox, SkyQ, FireStick, smart TVs and web, reaching millions of users.
• Developed and maintained video players (Shaka, hasplayer, dashplayer, exoPlayer).
• Contributed to streaming-protocol, CDN and playback-metrics architecture.

React, RxJS, MobX, TypeScript, Webpack, Sass, Serverless, Docker, Terraform, Node.js, Go, Drone, Jenkins, AWS

A property management platform.

• Developed isomorphic landing pages to improve user experience and performance.
• Built a React-based email service to streamline communications.
• Contributed to a B2B dashboard and payments service for enterprise users.

React, Redux, Webpack, Sass (BEM), Docker, Kubernetes, Node.js (Hapi.js, Express), Jenkins, AWS