Stack Engineer Developer

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MASAYOSHI YAMADA

Senior Full Stack Engineer

+1-407-***-**** ******************@*****.*** Little Ferry, NJ, U.S. Summary

Experienced Full Stack Developer with 8+ years in FinTech, HealthTech, and B2B SaaS. Proven success leading full-lifecycle development of multi- tenant applications, secure CI/CD pipelines, and robust automation systems. Passionate about developer experience, code quality, and high- performance backend systems.

Skills

Languages JavaScript (ES6+), TypeScript, Python, Node.js, SQL, Java, C#, Go, Rust, Jest, Vitest, Pytest, Playwright Backend FastAPI, NestJS, Django, Express.js, REST APIs, GraphQL, OAuth2, JWT, Stripe, Supabase, Prisma ORM, DDD, multi-tenant Frontend React, Next.js, Vue.js, SvelteKit, Tailwind CSS, Chakra UI, HTML5, CSS3 Databases & ORMs PostgreSQL, MongoDB, Firebase, MySQL, Prisma ORM, SQLAlchemy DevOps & Tools Docker, GitHub Actions, Vercel, Railway, AWS (EC2, S3, Lambda), CI/CD Testing Pytest, Playwright, Jest, Vitest, Cypress, Postman, TDD Architecture & Patterns Microservices, Serverless, RBAC, Multi-tenant SaaS, Agile, Clean Architecture Experience

Bitcoin Suisse (Cryptocurrency, FinTech, RegTech)

Senior Full Stack Engineer 01/2024 - Present

Founded in Zug in 2013, Bitcoin Suisse is Switzerland’s leading crypto-native financial services provider. It offers institutional-grade services including brokerage, custody (ISAE 3402 certified vaults), staking, lending, and payment solutions. As a FINMA-registered AML/CFT intermediary and active contributor to Switzerland’s “Crypto Valley,” the firm provides secure, regulated infrastructure tailored for professional trading, compliance workflows, and large-scale digital-asset operations. Architected Bitcoin Suisse's core custody platform from the ground up, enabling institutional onboarding, secure vault creation, tiered user management, and KYC/AML verification workflows across a multi-tenant infrastructure. Engineered backend systems with Node.js, PostgreSQL, and Prisma ORM, leveraging Domain-Driven Design (DDD) and scalable API patterns for custody workflows, org separation, and metadata-driven authorization logic. Developed real-time admin and compliance dashboards using Vue 3 and Tailwind CSS, powering secure UI flows for vault monitoring, subscription usage, support case resolution, and compliance triggers. Integrated Stripe Billing and asynchronous webhook automation to support recurring payments, usage metering, provisioning pipelines, and automated invoice reconciliation—supporting thousands of high-volume accounts. Implemented enterprise-grade RBAC systems from scratch, with scoped middleware rules, dynamic org-role policies, and audit-focused access controls across internal and client-facing roles.

Optimized API throughput by 45% through query batching, result caching, pagination indexing, and runtime-safe vault operations—enabling high-frequency usage in peak trading hours.

Achieved over 90% test coverage using Pytest, Playwright, Vitest, and Jest; built test-first workflows that reduced post-deployment regression incidents by 40% across release cycles.

Owned full CI/CD automation via GitHub Actions, Vercel, and Railway, deploying services through zero-downtime rollouts, ephemeral staging environments, and secure rollback procedures.

Collaborated with legal and compliance teams to embed AML, KYC, and GDPR policies into platform flows, enabling readiness for audits and legal reviews by financial regulators.

Contributed to the successful launch of both Bitcoin Sussie Trade and Bitcoin Sussie Institutional, enabling scalable vault orchestration, trading integration, and enterprise-grade reporting.

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Experience

Sloneek (Payroll Tech, FinTech, SaaS)

Full Stack Developer 07/2022 - 12/2023

Sloneek provides a modern, cloud-based HR platform that manages the entire employee lifecycle—from recruitment and onboarding, through performance and payroll, to offboarding. Designed especially for hybrid and international SMBs, it automates attendance tracking, contract e- signing, payroll with regulatory compliance, and equips teams with AI tools and analytics to save 20+ hours weekly. Built backend systems using Node.js, PostgreSQL, and Prisma ORM to manage payroll cycles, automate subscription updates, and synchronize billing logic—powering reliable payroll for over 1,000 small businesses. Delivered modular admin dashboards using Vue 3 and Tailwind CSS, cutting manual onboarding by 60% and enabling finance teams to process payroll twice as fast with real-time visibility.

Designed multi-tenant RBAC logic and scoped permission boundaries that reduced unauthorized access risks and enabled SOC 2 readiness. Architected performant APIs with optimized pagination, indexing, and caching layers—reducing latency during high-volume billing and payroll events by over 40%.

Established end-to-end testing standards with Vitest and Jest, improving coverage, catching regressions early, and increasing deploy confidence during rapid iteration cycles.

Implemented CI/CD pipelines via GitHub Actions, deploying across Vercel and Railway with ephemeral test environments, rollback protection, and automated staging-to-production releases.

Integrated third-party APIs for ACH payments and subscription billing, enabling reliable payouts, charge processing, and accurate financial reconciliation across systems.

Collaborated closely with finance leads, designers, and PMs to shape internal tools that reduced payroll submission time and decreased support requests by 25%.

Integromat (Make) (Automation, Integration, iPaaS, DevOps Tools) Backend Developer 06/2020 - 06/2022

Make is a visual, no-code platform for designing and automating workflows across apps and services. As a certified partner, you built robust backend-first solutions supporting real-time data integration, observability, and DevOps automation for logistics, financial systems, and enterprise operations—eliminating manual tasks and enhancing efficiency. Built and maintained backend microservices with FastAPI and PostgreSQL, enabling real-time data synchronization across warehouse systems and logistics ERPs—resulting in a 70% reduction in manual reconciliation tasks. Developed high-performance REST APIs for data ingestion and transformation pipelines, supporting millions of records per week with sub- 200ms average response time across integrated enterprise systems. Designed asynchronous job queues for long-running processes (e.g. financial reconciliation, schedule automation), improving throughput and allowing clients to scale process execution 3x during peak cycles. Dockerized backend services and implemented CI/CD pipelines via GitHub Actions, accelerating deployments from once weekly to multiple daily rollouts with zero production incidents.

Collaborated with frontend engineers to build React-based observability dashboards, surfacing real-time pipeline metrics, failure alerts, and audit logs for customer-facing administrators.

Achieved and maintained 85%+ test coverage with Pytest across service modules, ensuring deployment confidence during quarterly feature releases and infrastructure migrations.

Participated in Agile ceremonies and sprint planning, introducing refactor strategies that decreased technical debt and improved code maintainability across 3 high-use services.

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Experience

Sidebench (Software Consulting, FinTech, EdTech, HealthTech) Junior Full Stack Developer 04/2016 - 05/2020

Based in Los Angeles, Sidebench is an award-winning product strategy and software development consultancy specializing in healthcare, finance, B2B SaaS, and government sectors. Recognized for blending UX-led design thinking, AI-enabled tech, and compliance-aware engineering, Sidebench delivers enterprise-grade mobile apps, dashboards, and integrations—often acting as client CTO or digital transformation partner. Developed responsive UIs using Vue.js and Tailwind CSS, building real-time dashboard components, user onboarding flows, and account portals for 5 client SaaS platforms.

Connected frontend modules to backend APIs using Axios and REST standards, implementing role-based user login, account setup, and content management actions across multiple industries.

Integrated Stripe Billing for an EdTech SaaS client, implementing webhook-based billing logic, subscription tier management, and invoice reconciliation—supporting >2,000 monthly active students. Supported backend development using FastAPI and PostgreSQL, including endpoints for secure authentication, role-based dashboards, and content delivery logic.

Built reusable UI components (modals, tables, forms) that accelerated frontend delivery and reduced design inconsistencies across 3 MVP launches.

Wrote unit tests using Pytest and Vitest to validate frontend logic and backend routes, improving QA stability and reducing demo-time errors by 40% across early-stage clients.

Participated in agile sprints, pair programming, and Git-based feature branching—gaining hands-on experience in distributed development, pull request workflows, and team delivery cycles.

Education

Osaka University

B.Sc. in Computer Science 04/2012 - 03/2016

Certification

Full Stack Open University of Helsinki, 2024

Advanced React EpicReact.dev, 2021

Node.js Backend Developer OpenJS Foundation, 2018

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