Senior Backend Engineer - Fintech API & Quant Models

A financial services company; New York (NY); On-site; USD 140,000 - 190,000; Full time

Job summary

A financial services company in New York seeks an experienced Backend Engineer to design and deliver scalable backend services. You will drive technical direction, enforce engineering best practices, and collaborate across teams to build reliable software with a focus on financial calculations and pricing engines.

The role emphasizes C#/.NET (or Java), NoSQL data solutions, QuantLib usage, and observability integrations with Datadog/Elasticsearch, plus opportunities to mentor and adopt

Qualifications

• 5+ years of software development experience with a strong emphasis on backend engineering.
• Strong proficiency in C#/.NET backend development (Java acceptable).
• Proven experience designing and building APIs.
• Solid background in distributed messaging systems and event-driven architectures.
• Experience implementing financial calculations, pricing engines, or quantitative models in a capital markets or fintech environment.
• Hands-on experience with QuantLib or similar quantitative finance libraries.
• Experience with NoSQL databases such as MongoDB.
• Familiarity with telemetry and observability tools such as Sentry, Datadog, or Elasticsearch.
• Experience building and scaling component libraries or design systems.
• Familiarity with fixed income or securities pricing concepts. (nice to have)
• Familiarity with Pulsar, Databricks, or Lakehouse architectures. (nice to have)
• Hands-on experience with SignalR or WebSocket-based systems. (nice to have)
• Experience with AI-assisted development tools such as GitHub Copilot, Claude, or similar.
• Strong communication skills and a proven track record of cross-functional collaboration.

Responsibilities

• Design and develop high-quality backend services using C#/.NET or Java.
• Build and maintain ASP.NET service-side applications with a focus on scalability and long-term reliability.
• Work with distributed messaging frameworks and event-driven architectures to power high-throughput systems.
• Develop and optimize data solutions using NoSQL databases such as MongoDB.
• Design and implement financial calculation engines, pricing models, and quantitative algorithms with a strong emphasis on accuracy and performance.
• Utilize QuantLib or a comparable library to build and maintain pricing models, yield curve construction, and risk analytics components.
• Integrate and work with observability platforms such as Datadog or Elasticsearch to support system monitoring and diagnostics.
• Ensure numerical precision in financial computations, including proper handling of rounding, accruals, and market conventions.
• Collaborate with product, UI/UX, frontend, and DevOps teams to align on development and deployment strategy.
• Build reusable, testable backend infrastructure and uphold consistent coding standards across teams.
• Implement telemetry and monitoring best practices using Sentry or equivalent tools.
• Evaluate and adopt new technologies, frameworks, and design patterns to continuously improve engineering outcomes.
• Mentor engineers on backend development best practices and foster a culture of engineering excellence.
• Leverage AI-assisted development tools such as GitHub Copilot and Claude to improve productivity, code quality, and engineering workflows.
• Contribute to frontend solutions using React and Redux/Rematch where needed. (nice to have)

Skills

C#/.NET

API design

Distributed systems

NoSQL databases

QuantLib

MongoDB

Telemetry/Observability

GitHub Copilot

WebSockets/SignalR

Cross-functional collaboration

Tools

QuantLib

MongoDB

Sentry

Datadog

Elasticsearch

React

GitHub Copilot

Job description

A financial services company in New York seeks an experienced Backend Engineer to design and deliver scalable backend services. You will drive technical direction, enforce engineering best practices, and collaborate across teams to build reliable software with a focus on financial calculations and pricing engines.

The role emphasizes C#/.NET (or Java), NoSQL data solutions, QuantLib usage, and observability integrations with Datadog/Elasticsearch, plus opportunities to mentor and adopt