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)
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