Senior Fullstack Engineer (SDK)

TL;DR

Senior Fullstack Engineer (SDK): Designing and building a client-side JavaScript/TypeScript SDK for financial institutions, abstracting identity verification and fraud detection behind a unified API. Focus on architecting a secure, embeddable web application, owning end-to-end reliability for client-side code, and solving complex integration problems with third-party vendor SDKs.

Location: Hybrid role based in Berlin or London. No remote-only option for this position.

Company

hirify.global helps financial institutions make smarter, safer decisions with AI-powered software for automated decision-making.

What you will do

• Architect a client-side JavaScript/TypeScript SDK that orchestrates multiple third-party vendor scripts behind a unified, headless API.
• Build a secure, embeddable web application that renders interactive identity verification flows with a polished, brandable UX.
• Establish versioning strategies, staged rollouts, and CI/CD pipelines for client-side code running in customer browsers.
• Solve complex integration problems with various vendor SDKs and ensure they work seamlessly together.
• Collaborate with Product, Design, and customers to define the SDK's developer experience and shape the team's growth.
• Engage directly with early adopters to understand their integration environments and ensure flawless SDK operation.

Requirements

• Hybrid role based in Berlin or London, with regular in-person collaboration.
• Fluent English required for documentation, code reviews, and customer calls.
• Strong engineering fundamentals across the full stack, comfortable designing clean APIs and building responsive frontend experiences.
• Deep understanding of how browsers work, including the DOM, security models (CSP, CORS, iframe sandboxing), caching, and script loading.
• Experience operating systems in production and participating in incident response.
• 5+ years of professional software engineering experience, with at least 2 years building and shipping a client-side SDK, embeddable widget, or developer-facing JavaScript library for external consumers.

Nice to have

• Experience in identity verification, fraud prevention, or fintech, ideally with providers like Socure, Vouched, Onfido, Fingerprint, or ThreatMetrix.
• Familiarity with media APIs (camera access, image capture, WebRTC) and building permission-driven UX flows.
• Experience building developer tools, documentation, or SDKs with a focus on great developer experience.
• Previous experience as a tech lead or a strong desire to grow into one.
• Knowledge of security and compliance considerations (SOC2, PII handling) for client-side applications in regulated industries.

Culture & Benefits

• Work with colleagues who are capable, caring, and driven.
• Experience a flat hierarchy and direct communication with founding team members.
• Learn from experienced mentors and access a network of leading tech investors and advisors.
• Receive a top-of-market equity and cash compensation package.
• Get access to a self-development budget for conferences, books, or classes.
• Receive a new Apple MacBook Pro and a meaningful home office set-up.