iOS Developer (Frontend SDK)

Quantum Technologies. LLC; San Leandro (CA); On-site; USD 120,000 - 160,000; Full time

Job summary

A leading technology firm in California is seeking an experienced iOS Developer to design and develop high-performance mobile SDKs for payment solutions. This role involves optimizing SDK components, ensuring security compliance, and collaborating with product and backend teams to create innovative payment experiences. The ideal candidate has over 10 years of iOS development experience, expert-level Swift skills, and a strong background in mobile security mechanisms. A Bachelor's or Master's degree in Computer Science is preferred, with responsibilities including technical support and documentation creation.

Qualifications

• 10+ years of iOS development experience.
• Expert-level proficiency in Swift; working knowledge of Objective-C.
• Strong experience designing and maintaining mobile SDKs/frameworks.
• Hands-on experience with security mechanisms, REST APIs, and memory management.
• Strong communication, documentation, and problem-solving abilities.

Responsibilities

• Design, develop, and maintain iOS Frontend SDKs using Swift and/or Objective-C.
• Integrate payment and authentication APIs for secure transactions.
• Optimize mobile SDK performance and ensure compliance with security standards.
• Develop automated tests and documentation for SDK reliability.
• Collaborate with product and engineering teams to define solutions.

Skills

iOS development experience

Swift proficiency

Objective-C knowledge

Mobile SDKs/frameworks experience

Mobile security mechanisms

Performance tuning

REST APIs experience

Strong communication skills

Detail-oriented

Education

Bachelor’s or Master’s in Computer Science

Tools

Xcode

Swift Package Manager

CocoaPods

Instruments

XCTest

Job description

The client is seeking a highly skilled iOS Developer with strong expertise in building Frontend SDKs for high-scale, secure, and high-performance mobile applications. In this role, you will design, develop, and optimize iOS SDK components that power client’s next-generation payment experiences, digital wallets, authentication frameworks, and secure transaction flows.

You will collaborate closely with product managers, architects, backend platform teams, and client’s global developer ecosystem to build best-in-class mobile SDKs used by merchants, partners, and financial institutions worldwide.

Key Responsibilities

• SDK Design & Development: Design, develop, and maintain iOS Frontend SDKs using Swift and/or Objective-C.
• Build reusable client-side libraries, UI components, and frameworks for client’s mobile payment solutions.
• Ensure SDKs are lightweight, modular, scalable, and seamless for third-party integration.
• Integration & APIs: Integrate payment APIs, authentication APIs, and secure transaction services.
• Work with RESTful APIs, JSON data structures, and backend engineering teams to ensure smooth communication between systems.
• Provide technical support for internal and external partners integrating iOS SDK.
• Performance & Security: Optimize mobile SDK performance, startup time, and memory usage.
• Implement highly secure coding practices aligned with PCI-DSS and client’s internal compliance.
• Work with encryption modules, secure storage, tokenization, and device authentication.
• Testing & Documentation: Develop automated unit tests, UI tests, and integration tests for SDK reliability.
• Create comprehensive developer documentation, integration guides, and sample apps.
• Support continuous integration/continuous deployment (CI/CD) pipelines for SDK releases.
• Cross-Functional Collaboration: Partner with product, design, and architecture teams to define mobile-first solutions.
• Participate in code reviews, sprint planning, and Agile ceremonies.
• Provide mentorship to junior developers and contribute to engineering best practices.

Required Skills & Qualifications

• Technical Skills
• 10+ years of iOS development experience.
• Expert-level proficiency in Swift; working knowledge of Objective-C.
• Strong experience designing or maintaining mobile SDKs / frameworks.
• Hands-on experience with:
• • Xcode, Instruments, XCTest
  • Swift Package Manager / CocoaPods / Carthage
  • REST APIs & JSON parsing
  • Mobile security mechanisms (Keychain, certificates, OAuth, tokenization)
  • Memory management, performance tuning, multithreading (GCD/OperationQueue)

Domain Skills

Exposure to payment systems, digital wallets, or fintech applications is highly preferred.

Experience working with Visa, Mastercard, EMV, token services, or other payment ecosystems is a strong plus.

Soft Skills

Strong communication, documentation, and problem-solving abilities.

Ability to collaborate in a fast-paced, cross-functional environment.

Detail-oriented with a focus on secure and scalable engineering solutions.

Preferred Qualifications

Experience building SDKs adopted by large-scale developer communities.

Knowledge of cryptographic libraries, secure enclave, or authentication frameworks.

Familiarity with Agile, CI/CD, Git, Jenkins, or GitHub Actions.

Bachelor’s or Master’s degree in Computer Science, Engineering, or related field.

QUANTUM TECHNOLOGIES LLC is an equal opportunity employer inclusive of female, minority, disability and veterans, (M/F/D/V). Hiring, promotion, transfer, compensation, benefits, discipline, termination and all other employment decisions are made without regard to race, color, religion, sex, sexual orientation, gender identity, age, disability, national origin, citizenship/immigration status, veteran status or any other protected status. QUANTUM TECHNOLOGIES LLC will not make any posting or employment decision that does not comply with applicable laws relating to labor and employment, equal opportunity, employment eligibility requirements or related matters. Nor will QUANTUM TECHNOLOGIES LLC require in a posting or otherwise U.S. citizenship or lawful permanent residency in the U.S. as a condition of employment except as necessary to comply with law, regulation, executive order, or federal, state, or local government contract