Senior Software Engineer - Open Platform

With our growing customer base and our expansion into new markets and use cases, we have more to build than ever at Affinity as we execute on our vision to put relationship intelligence at every professional's fingertips.

As a Senior Software Engineer in the Open Platform team, you'll have the opportunity to push our product and platform in new directions while also shaping the next iterations of the features our customers already love. You will be one of our first team members in our brand-new Barcelona office. You'll help drive the technical roadmap and implementation of our Internal and External API layers, our 3rd party integration platform and access management systems.

We’re looking for a high-velocity engineer who thrives in dynamic environments—someone who can rapidly prototype end-to-end solutions, iterate quickly, and deliver measurable customer impact. From high-performing APIs to backend algorithms, integration frameworks, to guaranteeing data privacy with access management rules, you'll hone your skills across multiple domains while helping to drive forward the Affinity product and vision.

Location: Barcelona, Spain

For this role, we're embracing a hub-hybrid model, designed to balance flexibility with meaningful in-person collaboration. Team members in-office 2-days per week. We believe great things happen when people come together intentionally to connect, create, and build momentum as a team.

In this role, you will:

• Own product areas that are essential to the success of our customers and our business.

• Collaborate with world-class engineering, product, and design teams. You'll have the opportunity to learn from a wide variety of experiences and, of course, to share your own.

• Drive the technical best practices for our APIs, integrations and IAM systems that allow our platform to exceed its performance goals and customers expectations.

• Mentor other engineers to uplevel them individually and the team as a whole.

• Promote operational excellence with focus on high reliability, performance, and scalability

• Own and evolve our in-house authentication and authorization platform, including our custom auth server and client libraries.

• Design fine-grained access control systems — RBAC, permissions, and policy-based authorization — that scale across our multi-tenant customer base.

• Drive technical decisions on identity protocols, including OAuth2/OIDC, SAML, and JWT-based session and token management.

• Partner with security and platform teams to harden authentication flows and token lifecycle management at scale.

Qualifications:

Don’t meet every single requirement? Studies have shown that women and people of color are less likely to apply to jobs unless they meet every qualification. At Affinity, we are dedicated to building a diverse, inclusive, and authentic workplace, so if you’re excited about this role, but your past experience doesn’t perfectly align with the qualifications above, we encourage you to apply anyways. You may be just the right candidate for this or other roles.

• You have ~7+ years of experience in software engineering, with at least 2+ years of experience as a senior member of a team delivering end-to-end systems.

• You have hands-on experience building or maintaining authentication/authorization systems, ideally including custom-built auth servers or identity providers.

• You understand core identity protocols in depth: OAuth2/OIDC, SAML, JWT, and session/token lifecycle management.

• You've designed or extended RBAC or policy-based permission models and understand their tradeoffs at scale.

• You think adversarially about auth, reasoning through privilege escalation and access-control edge cases, not just the happy path.

• You’ve worked with a variety of web APIs and developed backend services using modern OOP practices.

• You have a strong understanding of relational databases and the ability to diagnose performance bottlenecks at the database layer.

• You’re comfortable troubleshooting across network, application, caching, queuing, and storage layers

• You've helped your teams solve high-scale challenges, integrate systems, or develop business intelligence platforms.

• You communicate nuanced ideas clearly, whether you're explaining technical decisions in writing or brainstorming in real time.

• You demonstrate strong ownership instincts and sweat the details.

• You’re excited to work on a cross-functional team, partnering with product stakeholders, other teams, and subject matter experts

• Language requirements: Proficient in English

Tech stack

Our systems are built in Ruby on Rails, PostgreSQL and Redis on the backend, and Typescript and React in the frontend. Our infrastructure is hosted by AWS and runs on Kubernetes. However, this role is more heavily focused on backend development, but will have some frontend development initiatives.

At Affinity, we may use artificial intelligence (AI) tools as part of our recruitment process to help screen and evaluate candidate applications. While AI assists our hiring team in managing applications efficiently, it never replaces decisions made by real people. We are committed to fair and transparent hiring practices, and our AI tools are regularly monitored to ensure they support - not replace - human judgment.

What you'll enjoy at Affinity:

• We live our values: As owners, we take pride in everything we do. We embrace a growth mindset, engage in respectful candor, act as playmakers, and "taste the soup" by diving deep into experiences to create the best outcomes for our colleagues and clients.

• Health Benefits: Comprehensive health insurance for both you and your family.

• Learning & Development: We provide an annual education budget and a comprehensive L&D program.

• Wellness Support: We provide a monthly budget for wellness memberships/equipment to support your overall health and happiness.

About Affinity

Affinity is the AI-first CRM for private capital, helping firms turn relationship intelligence into action across the investment lifecycle. Built on a decade of proprietary relationship, interaction and deal data, Affinity automatically captures activity, maps firm networks, and surfaces the connections and insights that help investors source, evaluate and win opportunities.

Trusted by more than 3,300 private capital firms, including 40% of the venture capital market and more than 330 private equity buyout teams, Affinity powers one of the industry's deepest relationship graphs. The platform is built on more than 130 billion structured relationships, 177 million people tracked, 88 million companies tracked and 31 billion interactions, helping firms uncover opportunities sooner, move with greater conviction and scale institutional knowledge over time.

Learn more: affinity.co