Senior Back End Developer

Define, design, and build APIs end-to-end in close collaboration with the U.S.-based Market Data team Develop and maintain serverless back-end services using Node.js and AWS Lambdas (or equivalent on GCP/Azure) Lead technical discussions on data contracts, integration patterns, and platform architecture Build robust, secure, and observable services with strong logging, monitoring, and error handling Optimize back-end performance, cost, and reliability across cloud-native infrastructure Leverage AI-powered tools (Claude, Gemini, ChatGPT, GitHub Copilot, etc.) to accelerate development and code review Mentor mid-level engineers, conduct code reviews, and define team standards and best practices

Advanced English skills with strong communication abilities. Self-motivated, proactive, and comfortable operating in fast-paced delivery environments. Thrives in collaborative, multicultural teams while maintaining strong individual ownership. Excellent analytical, problem-solving, and technical decision-making skills. Strong sense of accountability and product ownership. Technical Requirements 5+ years of professional experience in back-end development Strong proficiency in Node.js Hands-on experience with AWS Lambdas and serverless architectures Experience with cloud platforms: AWS, GCP, or Azure (AWS strongly preferred) Experience designing and building RESTful APIs and defining data contracts with consuming teams Hands-on experience using AI tools (Claude, Gemini, ChatGPT, GitHub Copilot, Cursor) in day-to-day development Experience with Git, CI/CD pipelines, and modern delivery workflows Solid understanding of authentication, authorization, and API security patterns (OAuth, JWT) Nice to have: experience with API gateways and observability tools (CloudWatch, Datadog) Nice to have: experience with Java or other back-end languages Nice to have: experience working with market data, financial data, or real-time data pipelines (futures, options, equities, FX, commodities) Nice to have: infrastructure-as-code experience (Terraform, CloudFormation, CDK)

Perks & Benefits working at Kopius! Results-Driven Culture: 100% remote, outcome-focused projects! Continuing Education: Ongoing training, workshops, and sponsored courses Career Growth: Abundant opportunities for development and advancement Language Learning: Online English classes to boost communication skills Referral Bonuses: Rewards for referring new talent The Box: Curated snack boxes and company swag every three months Keep Moving: Reimbursement for physical activity memberships About You | At Kopius, we value individuals who: Foster Community and Connection through teamwork and collaboration Create Exceptional Experiences by aligning communication and actions with excellence Embrace New Ideas, staying curious and adaptable Take Ownership, showing initiative and accountability Always Walk the Talk, upholding integrity in everything they do

We are seeking a Sr Back End Developer who can champion API design, scalability, and engineering excellence, helping the team build the back-end foundation of a new digital platform. This role supports a leading global derivatives marketplace headquartered in Chicago - an organization that operates some of the world’s largest futures and options exchanges across interest rates, equity indexes, FX, energy, metals, and agricultural commodities. This is a foundational role: you’ll be one of the first engineers on the project and will work directly with the client’s Market Data team to define and design APIs and data contracts that surface real-time and historical market information to institutional clients, traders, and partners. You’ll bring strong experience with Node.js, AWS Lambdas, and serverless architectures, excellent English communication, and hands-on expertise leveraging AI-powered development tools., At Kopius, we’re passionate about technology and committed to helping our partners innovate. With expertise in digital strategy, design, and engineering, our global team of nearly 600 professionals works on 40+ active projects worldwide. We thrive on solving complex challenges and building the future through thoughtful, high-impact digital solutions., © 2026 Careerjet All rights reserved