Contract Role: Senior Ember.js Engineer Outside IR35 fully Remote

Location: Remote (UK)

Duration: 2-3 months

Start: 21st July 2025

Engagement: Outside IR35

5 years plus Ember experience.

The Opportunity

A well-established financial services product business is looking for a Senior Ember.js Engineer to lead a critical upgrade project across its legacy Ember applications. These applications are part of a wider FX payments back-office platform, with components that have not been updated in several versions and are now reliant on unsupported versions of Ember.js and Node.js.

This is a focused engineering engagement. Youll work within a mono-repo ecosystem, modernising the codebase, resolving dependencies, and ensuring successful delivery of a clean, stable, and production-ready upgrade.

What is Required.

Working closely with internal engineering leadership and DevOps support, you will:

• Upgrade Ember.js from ~v3.20.5 to Ember 6.x (Octane) .
• Upgrade Node.js to v20+ across all associated packages.
• Migrate and validate shared packages within a monorepo (Lerna/Yarn Workspaces).
• Run and maintain comprehensive test coverage (unit, integration, and UAT).
• Identify and deprecate outdated libraries and plugins.
• Optionally consolidate common and domain-common packages into a single repo (without impacting delivery timelines)

Tech Stack:

• Frontend : Ember.js (Octane), Glimmer, Handlebars
• Tooling : Lerna, Yarn Workspaces, ESLint, Prettier
• Testing : QUnit, qunit-dom, ember-qunit
• CI/CD : AWS Amplify
• Auth : Keycloak (OAuth2 integration)
• Languages : TypeScript, JavaScript
• Misc : Ember Engines, Babel, Sass, ember-auto-import, ember-fetc

Skill-Set

• Deep experience upgrading and maintaining Ember.js applications (ideally 3.x ? 5.x/6.x).
• Solid grasp of Node.js environments and version migrations (especially v20+).
• Familiarity with monorepo structures , including Lerna and Yarn Workspaces.
• Experience working with Ember Engines and component libraries.
• Strong testing mindset youve worked with QUnit or equivalent test runners in Ember.
• Good communicator able to work autonomously and update stakeholders clearly.

Deliverables

• Technical Upgrade Plan
• Comprehensive Test Plan and Cases
• Clean builds and validated UAT release
• Post-upgrade performance and stability report

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