Senior Software Engineer / Core Product Systems

Calliere Group; New York (NY); On-site; USD 140,000 - 190,000; Full time

Job summary

Calliere Group in New York is seeking a senior backend engineer to join a small product team working on a high-volume B2B platform. You will own core services, design and deliver durable APIs and data models, and help raise engineering standards across the team.

You’ll collaborate with product, design, and customer-facing teammates, own architectural decisions, and mentor peers to ensure production-grade quality and reliability as the product scales.

Qualifications

• Strong fundamentals with good product judgment.
• Experience in backend/platform engineering in a growing product company.
• Building data-rich applications with complex business rules and transactions.
• Designing adaptable systems without over-engineering.
• Experience with cloud platforms and deployment practices.
• Writing clear technical documentation and explaining tradeoffs to others.

Responsibilities

• Design and deliver the services behind a sophisticated B2B platform.
• Build durable APIs, data models, and cross-service coordination.
• Improve developer tooling, production visibility, and operational confidence.
• Mentor teammates and raise the quality bar through reviews and collaboration.
• Participate in architecture decisions and help establish engineering patterns as the company grows.

Skills

Backend engineering

Platform engineering

APIs and data models

Service architecture

Debug production issues

Job description

A well-funded technology company is adding a senior engineer to a small product team building software for complex, high-volume business operations. The team works on the parts of the product that are hardest to get right: systems that transform messy inputs into dependable outputs, coordinate work across services, and give users confidence that important processes have completed accurately. If you enjoy backend engineering with genuine ownership—rather than shipping isolated tickets—this is a chance to help shape a product, its architecture, and the engineering standards around it.

The Role

You’ll design and deliver the services behind a sophisticated B2B platform. Your work will touch the product’s most foundational capabilities: representing customer-specific logic, coordinating work that spans multiple steps, and making the resulting behavior transparent to both internal teams and end users. You’ll be expected to work comfortably across the lifecycle: Dig into ambiguous requirements and turn them into practical technical plans Build durable APIs, services, and data models Make difficult processes resilient to failures, retries, and unexpected inputs Improve developer tooling, production visibility, and operational confidence Partner closely with product, design, and customer-facing teammates Participate in architecture decisions and help establish engineering patterns as the company grows Mentor teammates and raise the quality bar through thoughtful reviews and hands-on collaboration.

Requirements

This role suits an engineer who combines strong fundamentals with good product judgment. You don’t need to have worked in one particular sector, but you should recognize the difference between code that works in a demo and software that can be trusted in production. You may have experience with: Backend or platform engineering in a growing product company Building data-rich applications with complex business rules Relational databases, APIs, transactions, and asynchronous processing Service architecture, background jobs, queues, or event-driven systems Designing adaptable systems without over-engineering every edge case Debugging difficult production issues across application, data, and infrastructure layers Working with cloud platforms and modern deployment practices Writing clear technical documentation and explaining tradeoffs to non-specialists A strong candidate can take a broad product problem, identify the true constraints, and create a solution that is understandable for the next engineer to maintain.

Nice to Have Experience

Nice to Have Experience with Python, Go, Java, Ruby, TypeScript, C#, or another modern server-side language Familiarity with cloud infrastructure and production observability Experience working on workflow-heavy, data-intensive, or configuration-driven products Exposure to enterprise software, operations platforms, infrastructure tooling, or vertical SaaS

Interest in joining an in-person team in New York

How the Team Works

This is a high-ownership environment with a pragmatic, collaborative engineering culture. People are trusted to challenge assumptions, simplify complicated ideas, and take responsibility for outcomes—not just implementation. The company moves quickly, but it values careful thinking where it matters. There is room to influence both the product roadmap and the technical approach, particularly for engineers who enjoy getting close to real user problems.

Benefits Why This Is Worth a Look

You will have a meaningful seat at the table in a company solving non-trivial problems for serious customers. The work is technically substantial, commercially important, and broad enough to keep a strong backend engineer engaged. It’s a particularly good opportunity for someone who wants to build real systems, own difficult problems, and help a product team scale without losing the quality and care that made it successful in the first place.