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Senior Software Development Engineer (Platform & API Architecture)

Vaco
$75.00 - $85.00 / hr
United States, Wisconsin, Waukesha
Nov 18, 2025
Job Title - SR Software Development Engineer in Platform & API ArchitectureClient Location - Brookfield, WIWork Environment - Remote, with some travel to headquartersSalary - $150,000 to $180,000 plus bonus, plus benefits, and a lot moreTerm - Direct Hire"Please, no 3rd party companies are allowed to work on this position."You will help us build the platform that transforms how businesses and governments move money. The Opportunity

We're redefining how organizations manage deposits at scale. By combining fintech innovation, treasury intelligence, and secure infrastructure into a unified platform, we help public- and private-sector clients turn cash into a strategic asset-automating complex workflows with speed, accuracy, and real-time visibility.

We're launching the first version of our platform soon and stepping into a massive, underserved market. This is the rare moment where you can join early and help shape the architectural foundation of a high-growth fintech product-without the chaos of a true startup and with the impact of building an industry-changing platform.

If you're a builder at heart, someone who thrives in ambiguity and wants to create something entirely new, you'll be a perfect fit.

What Makes This Role Special
  • You'll architect the future of our platform-not inherit legacy.

  • You'll write code every day while guiding high-level design decisions.

  • You'll partner directly with the CTO and influence every primary technical choice.

  • You'll help define new revenue models: APIs, integrations, platform licensing, white-label solutions.

  • You'll build for scale in a regulated industry where reliability and security are everything.

This is the ideal role for an engineer ready to grow into an architect or platform owner.

What You'll Work On Platform & Architecture
  • Progress the platform from an internal system to a scalable, fully productized solution.

  • Architect for multi-tenancy, modular deployment, and white-label flexibility.

  • Build with future scale in mind-extensibility, observability, performance, and onboarding velocity.

  • Participate in architectural reviews and help define engineering standards.

API Ecosystem & Integration Strategy
  • Lead the design of robust REST APIs that connect to:

    • Banking systems

    • Retail POS infrastructure

    • Cash logistics providers

    • Public-sector financial systems

    • Own API versioning, governance, and lifecycle management as we scale to partner-facing services.

    • Build reusable, secure integration patterns for future enterprise customers.

      Financial Logic & Rules Engine
      • Extend our configurable rules engine to support complex financial workflows, including:

        • Reconciliation

        • Fee structures

        • Compliance logic and exception handling

        • SLA calculations

      • Build systems that enable non-engineers to configure business logic through UI- or DSL-based tools.

        Scalability, Security & Compliance
        • Design systems built for high availability and multi-client isolation.

        • Implement secure access controls, encryption, logging, and audit trails.

        • Architect for compliance with SOC2, PCI-DSS, and public-sector requirements.

        Leadership Without Management
        • Provide architectural guidance across the engineering team.

        • Translate customer needs and business problems into scalable technical designs.

        • Influence technical standards, code quality, and platform velocity.

        • Act as a strategic partner to leadership, exploring new delivery models.

        What You Bring
        • 6+ years in back-end engineering, with experience touching architecture or platform leadership.

        • Strong hands-on expertise withC# and.NET.

        • Proven success in building multi-tenant platforms, complex APIs, or B2B enterprise systems.

        • Deep understanding of:

          • API design & versioning

          • Modular/microservice architecture

          • Event-driven systems

          • Secure system design (OAuth2, JWT, RBAC, encryption)

          • Configurable business logic and rules engines

        • Experience working in regulated or compliance-driven environments is a strong plus.

          Why This Work Matters

          Every feature you build will directly shape how money moves through corporations, retailers, municipalities, and financial institutions. You'll help create the system that supports new business models, new customers, and the future of our platform.

          This is more than a senior engineering role-it's a chance to help architect a category-defining fintech product from the ground up

        Vaco by Highspring values a diverse workplace and strongly encourages women, people of color, LGBTQ+ individuals, people with disabilities, members of ethnic minorities, foreign-born residents, and veterans to apply.

        EEO Notice

        Vaco by Highspring is an Equal Opportunity Employer and does not discriminate against any employee or applicant for employment because of race (including but not limited to traits historically associated with race such as hair texture and hair style), color, sex (includes pregnancy or related conditions), religion or creed, national origin, citizenship, age, disability, status as a veteran, union membership, ethnicity, gender, gender identity, gender expression, sexual orientation, marital status, political affiliation, or any other protected characteristics as required by federal, state or local law.

        Vaco by Highspring and its parents, affiliates, and subsidiaries are committed to the full inclusion of all qualified individuals. As part of this commitment, Vaco by Highspring and its parents, affiliates, and subsidiaries will ensure that persons with disabilities are provided reasonable accommodations. If reasonable accommodation is needed to participate in the job application or interview process, to perform essential job functions, and/or to receive other benefits and privileges of employment, please contact HR@vaco.com .

        Vaco by Highspring also wants all applicants to know their rights that workplace discrimination is illegal.

        By submitting to this position, you agree that you will be giving Vaco by Highspring the exclusive right to present your as a candidate for the foregoing employment opportunity. You further agree that you have represented information about yourself accurately and have not affirmatively misrepresented your qualifications. You also agree to maintain as confidential, to the fullest extent permitted by law, any information you learn from Vaco by Highspring about the position and you will limit disclosure of information about the position only to the extent necessary to perform any obligations in furtherance of your application. In exchange, Vaco by Highspring agrees to exercise reasonable efforts to represent you through all solicitation, job screening and resume dispersal.

        Privacy Notice

        Vaco by Highspring and its parents, affiliates, and subsidiaries ("we," "our," or "Vaco by Highspring") respects your privacy and are committed to providing transparent notice of our policies.

        • California residents may access Vaco by Highspring HR Notice at Collection for California Applicants and Employees here.
        • Virginia residents may access our state specific policies here.
        • Residents of all other states may access our policies here.
        • Canadian residents may access our policies in English here and in French here.
        • Residents of countries governed by GDPR may access our policies here.
        Pay Transparency Notice

        Determining compensation for this role (and others) at Vaco by Highspring depends upon a wide array of factors including but not limited to:

        • the individual's skill sets, experience and training;
        • licensure and certification requirements;
        • office location and other geographic considerations;
        • other business and organizational needs.

        With that said, as required by local law, Vaco by Highspring believes that the following salary range referenced above reasonably estimates the base compensation for an individual hired into this position in geographies that require salary range disclosure. The individual may also be eligible for discretionary bonuses.

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