Black Tree Gaming Ltd
Principal App Engineer
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Location: UK or Europe
Salary: £80,000-£90,000
Please note: We are unable to sponsor international visas at this time.
About Nexus Mods
Established in 2001, Nexus Mods is the largest video game modding platform on the internet - a household name in the PC gaming ecosystem.
- 71M+ registered members
- 800K+ mods for 4,000+ games
- 21B+ mod downloads
We’re currently focused on product modernisation, driving growth and building infrastructure for the next 10 years of community-powered modding.
Our Role
We're looking for a Principal App Engineer to join our App Engineering team, working on Vortex, Nexus Mods' flagship desktop mod manager.
This is a hands-on, deeply technical role. You'll operate as a senior technical voice across the app, supporting the team technically while ensuring delivery is robust and aligned with our technical direction. You're expected to multiply the impact of the engineers around you through clear writing, mentorship, and the example you set in your own code.
Why this role is unique:
This is a chance to work on challenges most companies never encounter:
- A desktop application installed and run by millions of PC gamers on widely varying hardware and OS configurations.
- 500+ supported games, each with its own modding conventions, load order rules, file formats, and installer quirks.
- Deep operating system integration: native file systems, registry, drives, processes, code signing, and auto-update.
- A vibrant third party extension ecosystem built on top of a public API we own and evolve.
- A deeply engaged and passionate global modding community that ships, breaks, and rebuilds against every release.
From discovery and experimentation to delivery and scale, you'll play a key role in shaping systems that:
- Help millions of gamers install, sort, and manage mods effortlessly across hundreds of games.
- Empower extension authors and community developers to add new game support and features with confidence.
- Power complex, long running client side workflows - downloads, deployments, profile switching, conflict resolution.
- Bridge desktop and web through Nexus Mods' public APIs and auth.
- Enable rapid experimentation and iteration on new features without destabilising existing game support.
- Ensure the application evolves to support the next decade of growth in the modding ecosystem.
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Vortex's user base today is overwhelmingly on Windows, but Linux support is on the long-term roadmap. The engineering team already works across operating systems, so the codebase and tooling need to be portable from the start. We need someone to help move Vortex from Windows-first to properly cross-platform.
- Design and ship high-impact features and improvements across the Electron main process, renderer and extension surfaces.
- Tackle the hardest technical problems in the codebase - performance regressions, race conditions and complex state bugs.
- Drive architectural improvements that span multiple pods or feature areas, in coordination with engineering management.
- Set the bar for code quality through code review, design feedback, and exemplary PRs of your own.
- Mentor engineers at all levels, including formally and informally raising the team's expertise in Electron, React, TypeScript, and our domain.
- Steward the public extension API so third party authors can keep building against Vortex with minimal friction.
- Identify and pay down technical debt, legacy patterns, and scalability bottlenecks in long lived application code.
- Contribute to discovery, prototyping, and iterative delivery - including new game support and major workflow changes.
- Partner closely with Product, Design, QA, Community, and Backend disciplines to translate ambiguous problems into shippable solutions.
- Improve our tooling, build, packaging, and release pipelines so the whole team moves faster and more safely.
- Champion engineering standards - testing, observability, error reporting, accessibility, internationalisation - without turning them into bureaucracy.
Requirements
- Extensive application engineering experience, ideally with desktop, gaming, or creator tooling, at a level where you've consistently operated as a senior engineer on substantial systems.
- Deep experience with TypeScript and modern JavaScript in production.
- Strong experience with Electron across platforms: main vs renderer separation, packaging, signing, and auto-update. Comfortable reasoning about platform-specific behaviour in file systems, paths, permissions, and OS integration on Windows and Linux.
- Strong React experience, including state management.
- Solid understanding of Node.js internals, async patterns, streaming I/O, child processes, and native addon integration.
- Experience designing and evolving public APIs / SDKs consumed by external developers (backwards compatibility, versioning, deprecation).
- Strong system design and architecture skills applied to client side systems - module boundaries, plugin/extension models, data flow, persistence.
- Experience with packaging, code signing, and auto-update for production desktop apps (electron-builder, NSIS, Flatpak, or equivalent).
- Experience with CI/CD for desktop release pipelines, reproducible builds, and signed artefacts.
- A demonstrated track record of mentoring engineers and elevating the technical standard of the teams around you.
- Comfortable balancing speed, quality, and pragmatism in a long lived codebase with active community contributors.
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Bonus Skills
- Experience with authentication and download/distribution systems on the client side.
- Background in high scale desktop platforms, launchers, or content distribution clients (Steam, Epic, GOG Galaxy, Battle.net, modding tools, etc).
- Experience taking a Windows-first desktop app to Linux, or maintaining Windows/Linux parity in production.
- Understanding of gaming ecosystems: game file formats, save management, load orders, plugin systems.
- Experience building tools for creators, modding communities, or user-generated content platforms.
- Familiarity with Bethesda Creation Engine, FOMOD, Wabbajack or other established modding standards.
- Experience evolving a plugin / extension architecture with a public API and third party authors.
- Passion for gaming, modding, or creator ecosystems.
Benefits
- We work a 4-day week of 32 hours, with no reduction in pay.
- An allowance of £25 each month to spend on video games.
- Employee Assistance Programme.
- Private BUPA healthcare for you and your family.
- A very flexible training budget.
- Regular social events throughout the year. Participation is optional!
Diversity and Inclusion
We celebrate diversity and want you to bring your whole self to work.
Supporting an incredible community of tens of millions of users, we thrive on engaging as many views as possible to improve our platform. We see no reason why our culture should be any different.
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