Lex K

Senior Software Engineer

Craft

Aug 2025 - Aug 2026 • 1 yr

- Delivered Craft's centralized Identity service as primary engineer, supporting three products across at least three engineering teams. - Decoupled authentication from Portal and established a dedicated service with React, TypeScript, Node.js, and Express; implemented OpenID Connect Authorization Code flow with PKCE and a consistent Backend-for-Frontend architecture. - Moved OAuth access and refresh tokens into Redis-backed server-side vaults so browsers retained only HttpOnly session cookies; added refresh-token rotation, reuse detection, and single-flight refresh coordination. - Hardened identity controls by centralizing MFA setup, adding least-privilege database access and session denylisting, and requiring fresh organization-scoped tokens after organization changes. - Rolled Identity out fully to two products, Portal and Workspace, integrated Craft API, added extensive automated tests, and delivered through Craft's existing GitHub Actions, AWS, and Terraform infrastructure.

Lead Software Engineer

Fluyo

Aug 2020 - Jul 2025 • 4 yrs 11 mos

- Joined Fluyo before a product codebase existed in a concurrent long-term startup contract with variable commitment; built the initial TypeScript architecture across React Native, Node.js, GCP Cloud Functions, Firestore, Firebase Authentication and security rules, and Google Cloud Storage. - Independently delivered three major mobile iterations before the engineering team expanded and remained hands-on through the public iOS and Android launch. - Built reusable Three.js and React Three Fiber integration for animated 3D characters, then introduced shared model caching that measured approximately 3 times faster subsequent loading and rendering while reducing duplicate memory use. - Built core product systems including a learning journey with approximately 10 exercise formats, real-time social groups and moderation, user-created flashcards, and an authenticated React admin platform with schema-validated content ingestion. - Onboarded, mentored, and technically led three engineers in a four-developer team while remaining an active contributor. During the engagement, the product's Kickstarter raised $1.2 million from more than 8,000 backers.

Senior Software Engineer

HedgeFlows™

Jun 2021 - Jun 2025 • 4 yrs

- Joined HedgeFlows as the first technical hire for a UK B2B fintech platform, initially through an Artkai client engagement and later as a direct employee; built the initial React, Redux, and TypeScript customer application and admin panel, then expanded into Node.js, Express, GCP Cloud Functions, Firestore, Elasticsearch, and integrations. - Built and iteratively improved a Currencycloud-backed FX rate pre-booking flow across approximately three iterations, progressing from a multi-step frontend flow into backend integration, and extended existing Xero accounting workflows with read/write capabilities. - Designed an Elasticsearch read model and resilient Firestore-to-Elasticsearch synchronization with exponential-backoff retries, durable failed-record tracking, and scheduled replay that recovered real production sync failures. - Built GitHub Actions CI/CD pipelines from scratch for frontend and backend, with automated checks and staged promotion through QA and staging to production with manual approval. - Planned architecture and delivery work, reviewed code, onboarded two engineers, mentored one junior engineer, and conducted more than 50 technical interviews with assessments and recommendations.