ZipStaff Inc.
Senior Full Stack iOS Engineer
Washington, District of Columbia•Contract
$60 - $61 hourly
$60 - $61 hourly
About the Job
Job Title: Senior Full Stack iOS Engineer (AWS / Mobile-First)
Location: Washington, DC (On-site)
Employment Type: Contract (W2 through ZipStaff — No C2C or 1099)
Location: Washington, DC (On-site)
Employment Type: Contract (W2 through ZipStaff — No C2C or 1099)
About the Opportunity
ZipStaff is seeking a Senior Full Stack iOS Engineer to design, build, and maintain mission-critical, native frontline mobile applications and the supporting AWS cloud services for a leading transportation organization.
ZipStaff is seeking a Senior Full Stack iOS Engineer to design, build, and maintain mission-critical, native frontline mobile applications and the supporting AWS cloud services for a leading transportation organization.
In this role, you will lead the architecture of high-availability, offline-first passenger and employee operations, enabling reliable ticket scanning, real-time manifest tracking, peer-to-peer data synchronization, and secure backend integrations used daily by onboard conductors and station personnel. Working within an established Scaled Agile Framework (SAFe) environment, you will drive self-organized iteration planning, collaborate on resilient cloud/mobile contracts, and directly deliver seamless digital workflows where zero-downtime and data integrity are non-negotiable. This is an on-site role in Washington, DC.
What You’ll Do
- Architect, develop, and maintain high-performance native iOS applications utilizing Swift, applicable Objective-C, and modern concurrency models.
- Build robust, offline-first data architectures featuring local transactional queues, conflict resolution, reconnection/replay logic, and peer-to-peer sync mechanisms (e.g., Ditto, Infinite PeerConnect).
- Deliver end-to-end frontline workflows, including barcode/ticket scanning, passenger manifest management, check-in/lift states, and peripheral device integrations via Bluetooth.
- Design and integrate mobile clients with Backend-for-Frontend (BFF) REST APIs on AWS, leveraging OAuth/OIDC authentication, secure device storage, and request correlation.
- Implement reusable, configuration-driven UI components, feature flags, dynamic forms, and role-based workflows across supported iPhone and iPad devices.
- Instrument applications with Dynatrace mobile RUM, crash symbolization, privacy safeguards, and real-time performance telemetry.
- Partner with backend and platform teams on contract testing, API idempotency, and unified mobile-to-cloud data schemas.
- Champion Agile self-management within a SAFe structure—actively participating in capacity planning, iteration commitments, and onsite Program Increment (PI) planning events in Washington, DC.
Required Qualifications
- Proven track record building enterprise native iOS applications in production using Swift and Objective-C.
- Hands-on experience architecting offline-first mobile systems, Core Data persistence, local queueing, and peer-to-peer or edge synchronization frameworks.
- Practical backend experience designing or integrating AWS services, including API Gateway, Lambda, ECS Fargate, and Cognito/Entra ID (or Spring Boot microservices).
- Direct experience integrating external hardware peripherals (barcode scanners, sleds, or Bluetooth/BLE devices).
- Demonstrated knowledge of mobile performance optimization, thread safety, crash resilience, VoiceOver accessibility, and mobile monitoring tools like Dynatrace RUM.
- Familiarity with high-availability operational environments such as transportation, ticketing, reservations, or point-of-sale systems.
- Working knowledge of or formal training in SAFe (Scaled Agile Framework), with the ability to lead sprint commitments and capacity planning autonomously.
- Must be based within commuting distance of Washington, DC, available to attend key milestone ceremonies (such as PI Planning) onsite, and comfortable maintaining a camera-on collaborative presence during hybrid team sessions.
- Ability to work on-site in Washington, DC.
Preferred Qualifications
- Prior experience delivering offline-first mobile solutions for transportation, rail, or frontline operational environments.
- Hands-on experience with peer-to-peer synchronization frameworks and conflict resolution in production mobile apps.
- Strong background integrating mobile clients with AWS-based Backend-for-Frontend architectures.
- Experience instrumenting mobile applications with Dynatrace or similar real-user monitoring tools.
Benefits
- Health Insurance
- Dental Insurance
- Vision Insurance
- 401(k) + 401(k) matching
- Paid time off
- Referral Program
About ZipStaff
ZipStaff partners with leading organizations to connect skilled technology professionals with high-impact contract opportunities. We focus on quality matches, clear communication, and long-term success for candidates and clients.
ZipStaff partners with leading organizations to connect skilled technology professionals with high-impact contract opportunities. We focus on quality matches, clear communication, and long-term success for candidates and clients.
To apply, submit your resume highlighting your production native iOS (Swift/Objective-C) experience, offline-first architectures with peer-to-peer sync, AWS backend integration, and work in high-availability operational environments. Pure research or junior experience will not be considered.