James Chancellor, Developer in Brighton, United Kingdom
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James Chancellor

Verified Expert  in Engineering

Senior Back-end Developer

Brighton, United Kingdom
Toptal Member Since
September 17, 2020

James is a senior full-stack developer with several years of robust and hands-on back-end and DevOps experience. James is the type of developer who puts business value first, communicates openly and proactively across teams, is pragmatic with tools and languages, learns new ones quickly, and instinctively shares knowledge and mentors others.


Back-end, Node.js, JavaScript, Terraform, DevOps, Google Cloud Platform (GCP)...
Daily AI LLC
APIs, Node.js, REST APIs, TypeScript, Serverless Architecture, GraphQL, MongoDB...
Flux Vario
Java, Android, JavaScript, React, Express.js, PostgreSQL...




Preferred Environment

Amazon Web Services (AWS), JavaScript, TypeScript, Java, Linux, Node.js, React, Docker, Google Cloud Platform (GCP)

The most amazing...

...thing I've developed is Ski Nav, a mobile app for getting route directions on piste maps in resorts worldwide.

Work Experience

Full-stack TypeScript Developer

2023 - 2024
  • Developed core API endpoints in TypeScript/Express.js with integration tests.
  • Automated infrastructure deployment on the Google Cloud Platform (GCP) with Terraform and GitLab.
  • Implemented key UI designs for managing complex data structures in React.
  • Implemented load-balancer/SSL architecture and simplified serverless deployment options.
Technologies: Back-end, Node.js, JavaScript, Terraform, DevOps, Google Cloud Platform (GCP), React, Full-stack, Google Cloud Functions, API Gateways, Electron, GitLab, GitLab CI/CD, Deployment, Single Sign-on (SSO), WebApp, Desktop App Development

Node.js API Engineer

2023 - 2023
Daily AI LLC
  • Enabled call forwarding functionality with Twilio API.
  • Integrated the platform with Zapier, writing the app and webhook endpoints.
  • Improved integration with Encompass API, an industry-specific data source.
Technologies: APIs, Node.js, REST APIs, TypeScript, Serverless Architecture, GraphQL, MongoDB, Vercel, OpenAPI, Prisma, Next.js

Independent Android App Developer

2022 - 2022
Flux Vario
  • Created an Android variometer app for paraglider pilots that instantly measures the climb rate.
  • Designed a sophisticated sensor-fusion algorithm and low-latency audio pipeline.
  • Combined performant Java sensor/audio code with React/JavaScript UI.
  • Managed free trials with basic Express/TypeScript/Docker/GCP back end.
Technologies: Java, Android, JavaScript, React, Express.js, PostgreSQL, Google Cloud Platform (GCP), Docker, SVG, Audio, APIs, JSON, API Integration, Architecture, Front-end, Unit Testing, DevOps Engineer, Serverless Architecture, Back-end, DevOps, REST, Deployment, WebApp

Software Developer

2020 - 2021
  • Developed core features of a Java/Mongo API and Play web UI.
  • Introduced a new automated API test suite, enabling faster and more confident development.
  • Integrated rapidly with third-party APIs, allowing onboarding of new clients ahead of schedule.
  • Made large performance improvements by identifying missing DB indexes, algorithmic inefficiencies, and more compact data formats, thereby enabling the support of important future clients.
Technologies: Java, Play, Play 2, Gradle, MongoDB, Git, REST APIs, APIs, JSON, API Integration, Microservices, Integration Testing, Unit Testing, Java 11, Back-end, REST, WebApp

Independent Mobile App Developer

2019 - 2020
Ski Nav
  • Created a skiing app (iOS/Android) for point-to-point routing and locating friends in resorts worldwide. It had more than 5,000 downloads within the first few months of launch.
  • Identified needs not adequately met by existing apps.
  • Engaged with users to set product direction and adapt to feedback.
  • Implemented a vanilla JavaScript UI with a Three.js 3D map, showing solid core skills (ES8/CSS3).
  • Designed the code, features, UX, graphics, and marketing copy.
  • Chose a JavaScript/Node.js/Koa API, exploiting "universal" nature by sharing model code with the front end.
  • Used the simplest technologies required to solve the business problem: AWS Elastic Beanstalk, RDS (PostgreSQL), ElastiCache (Redis), and AWS SNS (WhatsApp-style authentication).
Technologies: Full-stack, Relational Databases, iOS, Android, Three.js, CSS, HTML, Cordova, TypeScript, JavaScript, SQL, Git, PostgreSQL, REST APIs, APIs, Redis, JSON, API Integration, Architecture, Front-end, Unit Testing, DevOps Engineer, Serverless Architecture, Amazon EC2, Redis Cache, Amazon RDS, Amazon CloudFront CDN, Back-end, DevOps, Networking, REST, Deployment, WebApp

Aerodynamic Modeler

2019 - 2019
Avian Hang Gliders
  • Created a computer model of hang glider dynamics to enable the optimization of handling/performance trade-off—a new approach in the industry.
  • Used Python, NumPy, and SciPy to directly implement a coupled finite element method (structural) and vortex lattice method (aerodynamic) system.
  • Implemented the large-deflection elasticity of a 2D surface in 3D space—not widely implemented in commercial FEM software.
Technologies: Aerodynamics, Finite Element Analysis (FEA), SciPy, NumPy, Python, Git, Docker, Unit Testing, Serverless Architecture, Back-end, Deployment

Software Developer

2017 - 2018
Genomics England
  • Introduced a large suite of automated tests to a large existing project which significantly improved quality.
  • Implemented authentication, pagination, and other BAU features of a Java and MongoDB-based web app.
  • Bridged the communications gap with the operations team to help enable rapid, reliable deployment of new code.
Technologies: OpenAPI, Swagger, MongoDB, Jersey, SaltStack, Apache Maven, Apache Tomcat, Java, Git, Microservices, Integration Testing, Unit Testing, Ubuntu, DevOps Engineer, Back-end, DevOps, REST, Deployment

Software Developer

2015 - 2016
Mendeley, Elsevier
  • Developed and maintained the core microservices that powered the Mendeley application.
  • Automated the provisioning and configuration of the build server infrastructure.
  • Mentored junior developers and improved the interview process.
Technologies: Microservices, Jetty, Test-driven Development (TDD), JUnit, Docker, Amazon Web Services (AWS), Relational Databases, Mockito, Apache Maven, Terraform, Jenkins, Elasticsearch, HBase, Dropwizard, Java, SQL, Git, MySQL, REST APIs, APIs, JSON, API Integration, Integration Testing, Unit Testing, Ubuntu, Bash Script, GitOps, DevOps Engineer, Amazon EC2, Amazon S3 (AWS S3), Redis Cache, Amazon RDS, Back-end, DevOps, Networking, REST, Infrastructure as Code (IaC), Single Sign-on (SSO), Deployment

Software Developer

2012 - 2014
Hotels.com, Expedia
  • Developed and maintained the core Java-based web services.
  • Performed a detailed analysis of geographic data during data-source migration to identify many sources of errors and hugely improve quality.
  • Contributed to key decisions concerning the design of new services.
Technologies: Test-driven Development (TDD), TestNG, Relational Databases, Spring, ActiveMQ, Apache Tomcat, Java, SQL, Git, MySQL, REST APIs, APIs, JSON, API Integration, Microservices, Integration Testing, Unit Testing, Bash Script, OpenAPI, Back-end

Software Developer

2009 - 2011
  • Led the production implementation of the 3D packing program, which determines the minimum number of containers required to hold the items for each order while optimizing several other constraints.
  • Implemented a detailed analysis of the above algorithm's performance to enable further optimization.
  • Led the second development phase of a system that directed staff from busier aisles to quieter ones.
Technologies: Relational Databases, Algorithms, Jakarta Server Pages (JSP), Java, SQL, Unit Testing, Bash Script, Back-end

Ski Nav

Ski Nav is an app for getting point-to-point route directions and sharing your location on a piste map. I was the sole person behind the app—designing the product, getting feedback from users, writing the code, marketing the app in the stores, creating graphical elements, managing deployment, and checking and fixing data. I always had to keep the bigger business picture in mind while working on complex technical problems, leading to an app with 5,000+ downloads in the first few months of launch.

Toptal React Academy

The Toptal React Academy is an exclusive learning program that teaches the React framework to select members of the Toptal network. After a month of study, all graduates are tasked with completing a 30-40 hour final project to build and deliver a React app from scratch.

Flux Vario

An Android variometer app for paraglider pilots. A variometer is an instrument that measures climb rate (vertical velocity), converts it into sound, and displays it visually, essential for pilots to stay aloft in rising columns of warm air without an engine. This app implements a sophisticated sensor fusion algorithm to combine barometer data with accelerometer and gyroscope data to give a more instant and accurate response than could be given with the barometer alone. This key feature means that an app can compete with instruments on dedicated hardware.
2004 - 2007

Master of Engineering Degree in Mechanical Engineering

University of Bristol - Bristol, UK


Toptal React Academy Graduate

Toptal, LLC


Node.js, REST APIs, NumPy, SciPy, OpenAPI, Three.js, React


Apache Maven, Git, Jenkins, Webpack, Apache Tomcat, SaltStack, Terraform, ActiveMQ, Babel, Jetty, Gradle, Amazon CloudFront CDN, Prisma, GitLab, GitLab CI/CD


Mockito, JUnit, Jersey, WebApp, Dropwizard, Spring, Jakarta Server Pages (JSP), Koa, Swagger, TestNG, Play, Play 2, Express.js, Electron, Next.js


JavaScript, Java, SQL, Java 11, TypeScript, HTML, CSS, Python, Bash Script, GraphQL


Microservices, Unit Testing, REST, Serverless Architecture, DevOps, Test-driven Development (TDD), Desktop App Development


MySQL, Relational Databases, JSON, MongoDB, PostgreSQL, HBase, Elasticsearch, Redis, Amazon S3 (AWS S3), Redis Cache


Linux, Amazon Web Services (AWS), Docker, Ubuntu, Amazon EC2, Android, iOS, Google Cloud Platform (GCP), Vercel


Algorithms, APIs, API Integration, Integration Testing, Back-end, Deployment, Critical Thinking, Full-stack, Architecture, DevOps Engineer, Amazon RDS, Engineering, Control Systems, Finite Element Analysis (FEA), Fluid Dynamics, Microcontroller Programming, Thermodynamics, Structural Analysis, Cordova, Aerodynamics, Sensor Fusion, Audio, SVG, User Interface (UI), Front-end, GitOps, Networking, Infrastructure as Code (IaC), Google Cloud Functions, API Gateways, Single Sign-on (SSO)

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