Senior Fullstack Engineer for Marketplace

Luxoft Holding; Brasil; Remote; BRL 180,000 - 320,000; Full time

Job summary

Luxoft in Brazil is seeking a senior full-stack engineer to build a platform enabling marketplaces, embeddable widgets, and partner integrations using TypeScript, React, and Python. You will work on OpenAPI contracts, SDK generation, and secure handling of PHI within HIPAA-like constraints.

You will ship via CI/CD, write tests, and own the end-to-end quality of the surfaces and API behind them, including the MCP server and AI-assisted tooling.

Qualifications

• 6+ years shipping production web applications.
• Experience building embeddable widgets or SDKs for third-party use.
• Strong TypeScript and React, plus Python backend.
• Experience with OAuth 2.0, OpenID Connect, and SSO.

Responsibilities

• Build embeddable widget as web components or iframes with strict isolation.
• Implement questionnaire and booking flows with WCAG 2.1 AA.
• Develop OpenAPI endpoints in Python services with tenancy and auth.
• Generate SDKs from OpenAPI specs and create developer docs.
• Ensure PHI handling and write tests across unit, integration, end-to-end.
• Contribute through CI/CD and participate in incident response.

Skills

Full-stack engineering

TypeScript

React

Python

OpenAPI

OAuth 2.0

Tools

FastAPI

OpenAPI tooling

CI/CD

Git

Docker

Job description

Project description

We're building a platform that companies use to create marketplaces that help people find the right kind of provider and book an appointment. Payer and employer partners deliver it to their members inside their own sites and apps, through embeddable experiences, SDKs, an API, andan MCP server.You'll build those surfaces and the API behind them. The work spans the embeddable widget clients place on their sites, the preview app that demonstrates it, the questionnaire and booking flows, SDKs, and a remote MCP server.This is a hands-on, AI-native role: you'll use coding agents and reusable AI skills every day to ship faster without trading away quality or security.

Responsibilities

• - Build the embeddable widget as web components or iframes, with style isolation, Content Security Policy compatibility, a postMessage protocol, and versioning that won't break partner pages.- Build the questionnaire and booking flows, white-label theming, and the preview app, to WCAG 2.1 AA.- Implement endpoints in the shared OpenAPI contract, in Python services, including tenancy and partner authentication.- Generate SDKs from the OpenAPI contract, write developer documentation, and build the sandbox experience for partner developers.- Ensure proper handling of PHI.- Write unit, integration, and end-to-end tests, ship through CI/CD, monitor what you build, and support incident response.

SKILLS

Must have

• - 6+ years of full-stack engineering experience shipping production web applications.- Experience building embeddable widgets, third-party-hosted web components, or SDKs that run inside other companies' products.- Strong TypeScript and React, plus backend services in Python (e.g., FastAPI).- Command of the web platform for embedding: custom elements and Shadow DOM, iframe sandboxing, Content Security Policy, and postMessage.- REST API design with OpenAPI, including SDK generation from specs. GraphQL experience is a plus.- Practical knowledge of OAuth 2.0, OpenID Connect, and SSO.- Experience working with PII and/or PHI under HIPAA.- Daily use of AI coding tools like Claude Code, with the judgment to keep AI-assisted code correct, tested, and secure.- You drive work to landed, not merged, and you own the result.

Nice to have

• Experience in healthcare technology and working PHI under HIPAA.
• Familiarity with FHIR, especially rendering FHIR SDC / Questionnaire resources, and with SMART on FHIR.
• Experience building MCP servers or other LLM tool integrations.
• Experience with micro-frontend architectures.
• Experience with scheduling or booking products.
• Experience with GraphQL or product analytics governance.