Braintrust
Senior iOS Developer, Contract (Remote, LATAM, Europe, Canada, US)
BraintrustRomania1 day ago
ContractRemote FriendlyEngineering, Information Technology
Job Description

  • Please note: This is a part-time (20 hours/week), 3-month contract.***** The role is open to candidates based in Latin America, Europe, Canada, and the United States. You must be available to work EST hours.

Interview process: 2-3 interview rounds.

Role Overview

We are looking for a Senior iOS Developer to support a high-priority mobile app stabilization and modernization initiative for an enterprise field operations product. The app is offline-first, used in real-world field conditions, and sync reliability is mission-critical. Users may collect a large volume of work offline, including photos and field data, and rely on the application to safely sync that work back to backend systems.

This role will focus on improving the reliability, observability, and maintainability of the iOS application, with particular emphasis on sync hardening, data-loss prevention, telemetry, rate limiting handling, media upload resilience, and floor plan/floor map feature stability.

The ideal candidate has deep iOS engineering experience, strong debugging and architecture instincts, and proven experience working on offline-capable apps with complex sync behavior.

Key Responsibilities

  • Analyze and improve the reliability of the iOS app’s offline queue and sync engine
  • Prevent data loss by ensuring failed sync operations remain retryable and are not silently discarded
  • Refactor and harden networking and retry logic, including proper handling of timeouts, 429 responses, and server backoff headers
  • Implement or improve sync telemetry, including session tracing, failure categorization, queue metrics, and support diagnostics
  • Support integration of batch sync APIs, including deterministic ordering, idempotent retry behavior, and partial failure handling
  • Improve media upload flows for large image sets, including interruption-safe retries and safe local retention until upload confirmation
  • Partner with backend engineers to validate request/response contracts and rollout behavior
  • Help stabilize and align the floor plan / overlay rendering implementation on iOS
  • Participate in architecture discussions and provide input on modernization options, including future React Native feasibility
  • Contribute to quality improvements, release readiness, and troubleshooting in staging and production environments

Required Qualifications

  • 5+ years of professional iOS development experience
  • Strong proficiency in Swift
  • Experience with UIKit in production applications
  • Experience working with local persistence technologies such as Realm, Core Data, SQLite, or similar
  • Strong experience with offline-first or occasionally connected mobile applications
  • Proven track record designing or maintaining sync workflows, retry logic, queue-based processing, or data reconciliation
  • Experience with REST APIs, authentication, network diagnostics, and error handling
  • Familiarity with file and image upload workflows on iOS
  • Experience implementing logging, telemetry, or observability for mobile systems
  • Ability to work in an existing codebase, diagnose issues quickly, and ship targeted reliability improvements

Preferred Qualifications

  • Experience with Alamofire
  • Experience with MapKit or custom overlay/map rendering
  • Experience with background processing, resumable tasks, or long-running sync flows on iOS
  • Familiarity with Sentry or similar error monitoring tools
  • Experience in construction tech, field operations, or enterprise B2B mobile products
  • Experience contributing to CI/CD pipelines, test automation, or release hardening

Key Skills

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