Senior iOS Engineer

Knot; New York (NY); On-site; USD 150,000 - 210,000; Full time

Benefits offered by this job

Competitive base salary + up to 20% annual bonus

Generous employee equity

Unlimited PTO

100% medical, dental, and vision insurance coverage

Food (snacks and meals for late workers)

Job summary

A leading financial technology company based in New York seeks a Senior iOS Engineer to lead the architecture and optimization of their iOS SDK, essential for large-scale FinTech applications. This role requires strong debugging skills, in-depth knowledge of iOS frameworks, and experience with CI/CD pipelines. The company offers a competitive salary, bonus potential, comprehensive insurance coverage, and unlimited PTO in a vibrant NYC office setting.

Qualifications

• Strong debugging skills and proficiency with native profiling tools.
• Deep understanding of memory allocation, leaks, CPU usage, and asynchronous patterns.
• Comfortable executing thorough QA validation prior to releases.
• Experience building and maintaining iOS libraries or SDKs.

Responsibilities

• Lead and contribute to architecture and optimization of the iOS SDK.
• Profile, debug, and improve memory usage and CPU consumption.
• Design stable public APIs and produce documentation for developers.
• Strengthen test coverage with unit tests, UI automation, and performance tests.
• Co-own mobile CI/CD workflows for safe releases.

Skills

Debugging skills

Proficiency with native profiling tools

Understanding of memory allocation

Experience building asynchronous architectures

Unit testing mindset

Clear communication

Experience with UI automation tests

Tools

Swift

Xcode

WKWebView

CI/CD pipelines

Job description

About Knot

Knot’s mission is to empower consumers and businesses alike with connected merchant and banking experiences. Knot is like “Plaid for merchant connectivity.” We are building the platform connecting merchants to the many applications that consumers and businesses interact with everyday. Our flagship CardSwitcher product allows consumers to instantly update & manage their cards on file with online merchant accounts (e.g. Netflix or PayPal), while newer products like TransactionLink support the retrieval of receipt‑level transaction data and AgenticShopping enables 1‑click, native shopping experiences.

Founded in 2021, Knot was founded by two brothers and Thiel Fellows – Rory and Kieran O’Reilly – and today powers connected online payment experiences for hundreds of thousands of consumers. Companies like American Express, PayPal, Current, BILT, Step, and more choose to embed Knot’s SDK in their apps to power best‑in‑class experiences for their customers.

Knot is proudly backed by a select group of investors, including Nava Ventures, 8VC, American Express, Plaid, and co‑founders & CEOs of prominent companies like Twitter, Warby Parker, Allbirds, Casper, Intercom, Deel, Italic, DraftKings, and many more.

About the role

We are looking for a Senior iOS Engineer to help shape the architecture, reliability, and performance of our SDK, which powers mission‑critical experiences for some of the largest FinTechs in the world.

You will work across the entire lifecycle of our iOS SDK, from design to release. This includes shaping how we profile performance, how we catch issues before they ship, how we test our public APIs, and how we produce documentation that makes our SDK easy to integrate. You will collaborate with product and engineering teams across the company, and you will help represent and advocate for our SDK both internally and externally.

What you’ll be doing

• Lead and contribute to the architecture, design, and optimization of the iOS SDK
• Profile, debug, and improve memory usage, CPU consumption, concurrency, and overall runtime efficiency
• Design stable, predictable public APIs and produce documentation that supports developers integrating our SDK
• Strengthen test coverage with unit tests, UI automation, integration testing, and performance testing
• Co‑own the mobile CI/CD workflows that ensure safe, reliable, and repeatable releases
• Investigate production issues with attention to detail and implement long‑term safeguards
• Advocate internally and externally for best practices around integration, performance, and reliability
• Participate in cross‑team technical planning and represent the platform’s needs
• Evangelize the SDK and help educate teams on its capabilities and usage
• Contribute to building an engineering culture rooted in clarity, ownership, and thoughtful design

What you’ll need to get the job done

• Strong debugging skills and proficiency with native profiling tools
• Deep understanding of memory allocation, leaks, CPU usage, and asynchronous patterns
• Experience building asynchronous and multithreaded architectures
• Ability to design, validate, and document public SDK APIs
• Strong unit testing mindset and experience uncovering failure modes and edge cases
• Familiarity with mobile CI/CD pipelines and the desire to improve them
• Comfortable executing thorough QA validation prior to releases
• Clear and effective communication with cross‑functional teams
• Experience writing and debugging UI automation tests
• Familiarity with feature flagging and controlled rollout strategies

iOS Specific Skills

• Deep experience with WKWebView including navigation, messaging, resource handling, and hybrid debugging
• Proficiency with Swift and Swift Concurrency
• Experience with ARC, Instruments, and iOS frameworks
• Experience building and maintaining frameworks or Swift Packages
• Familiarity with Xcode build tooling and performance optimization

What we offer

• Interesting and challenging work
• Competitive base salary + up to 20% annual bonus + generous early employee equity + benefits
• 100% medical, dental, and vision insurance coverage for you and your dependents (U.S.)
• Unlimited PTO
• Parental leave
• Beautiful NYC office in the heart of Flatiron
• Herman Miller Aeron desk chair
• Food (snacks, frequent lunches & often dinner for those working late)