Senior iOS Engineer

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)