Senior Software Engineer - Banking Integration Platform
WFA Digital Insight
The demand for skilled software engineers in fintech grew 25% in 2025, driven by the need for secure and efficient digital payment systems. With the rise of online banking, companies like Mercury are building modern, product-focused engineering systems to connect with traditional core banking systems. As a senior software engineer in this space, you'll need expertise in handling complex integrations, designing internal APIs, and building reliable data pipelines. Candidates should be aware that this role requires a deep understanding of core banking systems and experience with FFIEC-compliant bank cores. Before applying, consider your ability to thrive in a fast-paced environment and build something new, rather than maintaining existing systems.
Job Description
About the Role
Mercury is building a bank, and as a Senior Software Engineer on the Banking Integration Platform as a Service team, you'll play a crucial role in connecting the company's modern engineering systems to enterprise core banking systems and payment networks. This is some of the most consequential infrastructure work at Mercury, and every account opening, monetary transaction, and balance call will flow through the systems you build. You'll be one of the few engineers at Mercury who truly understand the full depth of the Bank Core and its internal and external integrations.The team is responsible for building integration subsystems that are technically correct and operationally trustworthy, much like NASA's Rendezvous, Proximity Operations, and Docking (RPOD) subsystems. You'll need to handle the messy realities of enterprise integrations, such as retries, failures, format mismatches, and downtime, and design internal APIs that give product teams simple, consistent interfaces to complex external systems.
As a senior software engineer, you'll be working closely with many other teams at Mercury to define clean boundaries and reliable contracts. Your work will have a significant impact on the company's ability to provide secure and efficient digital payment systems to its customers.
What You Will Do
- Build Mercury's integration with an FFIEC-approved bank core and connections to payment networks
- Design internal APIs that give product teams simple, consistent interfaces to complex external systems
- Handle the messy realities of enterprise integrations, such as retries, failures, format mismatches, and downtime
- Build data pipelines that keep Mercury's systems in sync with the bank core
- Own monitoring, alerting, and recovery for the most critical external connections
- Partner with many other teams at Mercury to define clean boundaries and reliable contracts
- Help shape the technical architecture of Mercury Bank
- Collaborate with cross-functional teams to identify and prioritize project requirements
- Develop and maintain technical documentation for the integration platform
- Participate in code reviews and ensure that the codebase is maintainable, efficient, and scalable
What We Are Looking For
- Direct experience with either a bank core that has achieved FFIEC-compliance or that of a US-based Global Systemically Important Bank (G-SIB)
- Understanding of how core banking systems work, including accounts, transactions, ledgers, and data models
- Product-minded engineer who thinks about the developers consuming your APIs, not just the systems you're connecting to
- Ability to thrive in environments where you're building something new, rather than maintaining something established
- Comfort with the tech stack (Haskell and TypeScript) or readiness to learn
- Strong opinions about building reliable, maintainable systems
- Experience with building and maintaining large-scale distributed systems
- Knowledge of cloud-based technologies and containerization (e.g., Docker, Kubernetes)
- Familiarity with agile development methodologies and version control systems (e.g., Git)
Nice to Have
- Experience with DevOps practices and tools (e.g., Jenkins, CircleCI)
- Knowledge of security best practices and compliance frameworks (e.g., PCI-DSS, HIPAA)
- Familiarity with messaging queues (e.g., RabbitMQ, Apache Kafka) and streaming data platforms (e.g., Apache Kafka, Amazon Kinesis)
- Experience with building and deploying machine learning models
- Certification in a relevant field (e.g., cloud computing, cybersecurity)
Benefits and Perks
- Competitive salary and equity package
- Comprehensive health, dental, and vision insurance
- 401(k) plan with company match
- Flexible PTO policy and paid holidays
- Remote work stipend and home office setup support
- Professional development opportunities and conference sponsorships
- Access to a diverse and talented team of engineers and professionals
- Opportunity to work on challenging and impactful projects that can change the fintech landscape
How to Stand Out
- To stand out in this role, make sure you have a deep understanding of core banking systems and experience with FFIEC-compliant bank cores.
- Be prepared to explain your approach to handling complex integrations and designing internal APIs.
- Familiarize yourself with Mercury's tech stack (Haskell and TypeScript) and be ready to learn.
- Highlight your experience with building and maintaining large-scale distributed systems and your knowledge of cloud-based technologies.
- Be prepared to discuss your opinions on building reliable, maintainable systems and how you would approach this in the context of Mercury's banking integration platform.
- Make sure your resume and online profiles are up-to-date and showcase your relevant skills and experience.
- Research the company culture and values to ensure you're a good fit for the team and can thrive in the fast-paced environment.
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