In the fast-paced world of fintech, technology decisions can make or break a company's ability to innovate, scale, and compete. When Funding Circle, a peer-to-peer lending platform that has lent over $500 million to more than 5,000 companies, decided to expand their tech stack from Ruby to include Clojure, it wasn't just about adding another programming language—it was a strategic decision with far-reaching implications.
Let's dive into the technology journey that helped Funding Circle scale their platform while maintaining the agility needed in the financial services sector.
Like many innovative startups, Funding Circle initially built their platform using Ruby, leveraging its readability, clean syntax, and robust ecosystem that makes web development remarkably efficient.
Ruby's advantages are well-documented:
As Denislav Naydenov, a Tech Lead at Funding Circle explains:
For a fintech startup moving fast to capture market share, these qualities were invaluable. However, as Funding Circle grew exponentially, new technical challenges emerged.
By 2015, Funding Circle was processing millions in loans and managing complex financial data flows. They faced new requirements:
While Ruby had served them well for traditional web applications, these new demands required additional capabilities. Enter Clojure.
Denislav Naydenov shares the reasoning:
Clojure brought specific advantages that complemented Ruby:
As Denislav notes:
Crucially, Funding Circle didn't abandon Ruby—they embraced a polyglot approach where each language served its purpose:
This strategic decision allowed Funding Circle to continue leveraging their engineers' expertise in Ruby while gradually building Clojure capabilities for specific domains.
The expansion to Clojure had significant implications for team building:
Funding Circle's team at Pwrteams evolved into specialised squads focused on different technology areas:
This specialisation allowed each group to develop deep expertise in their domain while maintaining cross-team collaboration.
Adding Clojure to the stack required a deliberate talent acquisition approach. While Ruby developers were relatively abundant, experienced Clojure developers were scarcer.
Funding Circle adopted a two-pronged strategy:
Pwrteams supported this strategy by:
The technology expansion reinforced a learning culture within the engineering team. As Hristo Stamenov, a Senior Front-end Developer at Funding Circle team, notes:
This culture of continuous learning became a powerful recruitment and retention tool, attracting developers who wanted to expand their skills while working on meaningful financial products.
The addition of Clojure enabled Funding Circle to implement sophisticated architectural patterns better suited to financial systems:
Key architecture components include:
This architecture delivered critical benefits for a financial platform:
Funding Circle's technology evolution offers valuable lessons for technology leaders navigating similar decisions:
Funding Circle didn't add Clojure because it was trending—they identified specific technical challenges where Clojure's strengths aligned perfectly with their needs.
Key takeaway: Start with the problem, not the technology. Choose tools that address your specific challenges rather than following industry hype.
Rather than forcing a one-language-fits-all approach, Funding Circle embraced a polyglot strategy where multiple technologies coexisted, each serving the purposes where they excelled.
Key takeaway: Design your architecture to support multiple languages and frameworks, with clear boundaries between domains.
As Funding Circle's technology stack evolved, so did their team structure, with specialised squads developing deep expertise in specific domains.
Key takeaway: Align your organisational structure with your technology architecture to maximise effectiveness.
Working with us gave Funding Circle access to specialised recruiting capabilities that could find and attract scarce Clojure talent.
Key takeaway: Consider strategic partnerships for accessing specialised talent pools, especially when expanding into technologies with limited talent availability.
The technology stack evolution delivered tangible business results:
Georgi Kostov, a Tech Lead at Funding Circle, summarises the impact:
Every growing company faces similar decisions about when and how to evolve their technology stack. Funding Circle's journey demonstrates that technology evolution can become a powerful competitive advantage with thoughtful planning, the right talent strategy, and appropriate technical partnerships.
Is your organisation considering a similar technology expansion? Let's discuss how building the right team can support your technology strategy.