macOS Extension Developer (Contractor)

About us

Working at Tech Holding isn't just a job, it's an opportunity to be a part of something bigger. We are a full-service consulting firm that was founded on the premise of delivering predictable outcomes and high-quality solutions to our clients. Our founders and team members have industry experience and have held senior positions in a wide variety of companies – from emerging startups to large Fortune 50 firms – and we have taken our combined experiences and developed a unique approach that is supported by the principles of deep expertise, integrity, transparency, and dependability.

The Role

We are looking for a senior macOS systems engineer with deep expertise in file system extensions and kernel-adjacent frameworks. You will be responsible for building and maintaining a production-grade sync or virtual drive client on macOS, one that users depend on every day. This is a technically demanding role suited to an engineer who has shipped real software in this space and understands the nuances of Apple's extension model from entitlements to on-demand resource management.

Key Responsibilities

Design, implement, and maintain macOS File Provider extensions using NSFileProviderExtension and related APIs

Item enumeration, working set management, and placeholder lifecycle

On-demand downloading and eviction of file content

Conflict detection and resolution strategies

Integrate and maintain macFUSE-based virtual file systems

Implement low-level FUSE operations: read, write, getattr, readdir, open, release

Handle partial byte-range reads for large file streaming scenarios

Manage macOS System Extension lifecycle including code signing, notarization, entitlements, and sandboxing requirements

Build and maintain XPC services for secure inter-process communication between the extension and host app

Write idiomatic Swift using modern concurrency patterns (async/await, actors, structured concurrency)

Diagnose and resolve complex, hard-to-reproduce issues at the intersection of the kernel, file system, and user space

Collaborate with product and backend teams to define sync protocols and surface reliable UX

Required Skills

5+ years of macOS development experience, with a focus on system-level or framework-level work

Strong hands-on experience with the FileProvider framework

NSFileProviderExtension, NSFileProviderItem, and domain management

Item enumeration, on-demand download, and working set eviction

Conflict resolution and syncing state machines

Practical experience with macFUSE

Implementing core FUSE operations: read, write, getattr, open, readdir

Handling partial byte-range reads

Debugging kernel panics and FUSE-layer failures

Deep understanding of macOS System Extensions

Code signing and notarization workflows

Entitlement management and capability provisioning

Sandbox constraints and their impact on file system access

Proficiency with Swift async/await and XPC services for IPC

Has shipped a production macOS sync client, cloud drive, backup tool, or similar, that real users depend on

Nice-to-have Skills:

Experience with network file system protocols (WebDAV, SMB, NFS) at the application layer

Familiarity with FSEvents for file system monitoring

Prior experience with Endpoint Security or Network Extension frameworks

Contributions to open-source macOS tooling or FUSE projects

Background in cloud storage, backup, or enterprise file management products

Familiarity with TestFlight distribution and enterprise MDM deployment of system extensions

What we offer

Fully remote engagement across MX.

Opportunity to work on high-impact client systems with real operational ownership.

Employment type

Contract

Tech Holding is proud to be an Equal Opportunity Employer and is committed to fostering a diverse and inclusive workplace. We welcome applicants from all backgrounds and experiences, and we consider qualified applicants without regard to race, color, religion, gender, sexual orientation, gender identity, national origin, disability, veteran status, or any other legally protected characteristic. If you require accommodation in the application process, please contact our HR