Senior Software Engineer (Full-Stack, Backend, Frontend)

Onsite or remote • Karlsruhe+4💼 Full-time🗓 2026-06-24

Core

Designing and building scalable service & sales workflows, payment processing systems, and real-time features for a multi-tenant SaaS platform.

Role type

Senior Full-Stack Software Engineer (Backend & Frontend)

Builds

Order management, checkout flows, payment reconciliation, CRM/ERP integrations, and real-time notification systems.

Domain

Fintech / SaaS / E-commerce

Deliverable

production ML models | product features | infrastructure

Required skills

PHP/Laravel, React/Next.js, TypeScript, REST API design, MySQL, Redis, Azure cloud services, Docker, CI/CD pipelines, SQL optimization, system integration (webhooks/APIs), architectural decision-making, code review, testing strategies.

Preferred skills

Experience with multi-tenant architectures, event-driven sync, observability, mentoring.

Technologies

PHP, Laravel, React, Next.js, TypeScript, MySQL, Redis, Azure, Docker, GitHub Actions

Responsibilities

Own features from requirements through production including architecture and deployment; Build and maintain reliable backend services with documented REST APIs; Design and implement payment workflows ensuring correctness and traceability; Integrate third-party systems via APIs; Develop modern, accessible frontend components; Design and optimize data models for performance; Establish engineering best practices including Git workflows and testing strategies; Collaborate with customer stakeholders to align on technical trade-offs; Mentor team members and drive continuous improvement.

Seniority

Senior, hands-on IC with mentorship responsibilities

Rewrite

## About the role What You'll Build - Service & Sales Workflows — Order management, queue handling, status tracking, checkout, and payment processing - Payment Processing — Checkout flows, refunds, deposits, invoice generation, and reconciliation - System Integrations — Sync data with external CRM/ERP systems via REST APIs - Real-Time Features — Notifications, status updates, webhook processing, and event-driven sync - Data Layer — Schema design, migrations, and performance tuning (MySQL, Redis) - Cloud Infrastructure — Multi-tenant Azure deployments, storage, and identity management ## Your Responsibilities - Own features from requirements through production, including architecture decisions, implementation, testing, and deployment - Build and maintain reliable backend services with well-documented REST APIs (authentication, authorization, idempotency, error handling) - Design and implement payment workflows ensuring correctness, traceability, and observability - Integrate third-party systems via APIs (webhooks, retries, rate limits, lifecycle management) - Develop modern, accessible frontend components with React and TypeScript - Design and optimize data models (MySQL, Redis) with attention to performance and consistency - Establish engineering best practices: Git workflows, code review, testing strategies (unit/integration/E2E), CI/CD - Collaborate directly with customer stakeholders: lead technical discussions, present options, and align on trade-offs - Mentor team members and drive continuous improvement ## Your Profile - 5+ years of professional software engineering experience shipping and operating production systems - Strong PHP/Laravel skills for backend development - React/Next.js and TypeScript for frontend - Proven experience with Azure (App Service, Blob Storage, Identity) - Hands-on experience building APIs and third-party integrations (webhooks, retries, idempotency, versioning) - Solid SQL skills (MySQL preferred); understanding of performance and consistency trade-offs - Cloud-native operations experience with Docker; CI/CD pipelines (GitHub Actions)

Sourced via wellfound · Listed on CareerPlan, which tracks 70,000+ jobs from 20+ sources.