Matías Seijas
I’m Matías Seijas, a senior iOS software engineer who enjoys building reliable, user-focused mobile experiences—from core product workflows to cross-platform collaboration.
About
I’m Matías Seijas, a senior iOS software engineer who enjoys building reliable, user-focused mobile experiences—from core product workflows to cross-platform collaboration. I’ve led iOS initiatives ranging from invoicing and appointments to Mobile Check Deposit, partnering closely with engineering, product, design, and banking teams to ship stable, well-designed features across platforms.
Earlier in my career I worked at The Browser Company building browser features on macOS and Windows with Swift and modern Apple frameworks. I’ve also played major leadership roles, including spearheading Flutter adoption at Betterment and mentoring engineers, helping teams move faster while improving developer productivity through shared mobile platform abstractions and a cohesive design system.
- 10 years' experience
- Joined September 2026
Industry experience
- Software & Internet
- Computers & Electronics
- Financial Services
Work experience· 8 roles
Senior iOS engineer focused on Invoices and Appointments apps. Built and maintained core invoicing workflows to ensure reliability and a high-quality seller experience. Owned the iOS implementation of Mobile Check Deposit in partnership with the Square Banking team. Partnered cross-functionally with Android, Server, Banking, Risk, Product, and Design to align on API design, shape user-facing features, coordinate phased rollouts, and ensure production stability across platforms.
Built key browser features across platforms on macOS and Windows using Swift. Leveraged AppKit, SwiftUI, The Composable Architecture, Swift Concurrency, and Combine. Collaborated with design teams to improve onboarding and core product interactions. Adapted quickly to changing priorities by shifting resources to meet evolving timelines.
iOS lead for the Mobile Payment Experience team. Built internal and third-party developer SDKs to interact with Square’s various product offerings. Devised the team’s roadmap, deliverables, technical blockers, and timelines to ensure successful execution and collaboration across teams. Mentored engineers and supported their growth through the development process.
Education
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