Application Guide

How to Apply for Senior Backend Engineer (Ruby on Rails)

at Wunder Capital

🏢 About Wunder Capital

Wunder Capital is a cleantech startup accelerating solar energy adoption to combat climate change. They combine finance and technology to make solar development more accessible, and their engineering team directly impacts the clean energy transition. Working here means contributing to a mission-driven company that values sustainable impact.

About This Role

As a Senior Backend Engineer, you'll build and maintain the core systems that automate solar project evaluation, development, and loan servicing. Your work will directly enable faster deployment of solar energy by streamlining complex financial and operational workflows. This role offers high ownership and the chance to shape the technical direction of a growing platform.

💡 A Day in the Life

A typical day might start with a standup with the product team to discuss priorities, then diving into code to implement a new feature for automating solar loan approvals. You'll review pull requests from teammates, run tests in CircleCI, and collaborate on architecture decisions for scaling the platform. After lunch, you might pair with a product manager to refine requirements for a solar value evaluation tool, then deploy a bug fix before wrapping up.

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🎯 Who Wunder Capital Is Looking For

  • Has 5+ years of backend engineering experience, with deep expertise in Ruby on Rails and PostgreSQL, and has built scalable, well-tested systems.
  • Is experienced with CI/CD pipelines (e.g., CircleCI) and cloud platforms (Heroku, AWS) to ensure rapid, reliable deployments.
  • Is genuinely excited about cleantech and motivated to build technology that accelerates the clean energy future.
  • Thrives in a fast-paced startup environment, is team-oriented, and believes no problem is too hard to solve collaboratively.

📝 Tips for Applying to Wunder Capital

1

Tailor your resume to highlight Ruby on Rails and PostgreSQL projects, especially those involving automation or financial systems.

2

In your cover letter, explicitly connect your backend experience to the mission of accelerating solar adoption; show you understand the climate impact.

3

If you have experience with Hotwire (Turbo/Stimulus), mention it—it's specifically listed in the job description.

4

Demonstrate your experience with CI/CD by describing a specific pipeline you built or improved, mentioning tools like CircleCI.

5

Research Wunder Capital's product (solar loan servicing, project evaluation) and reference it in your application to show genuine interest.

✉️ What to Emphasize in Your Cover Letter

['Emphasize your passion for cleantech and how your backend skills can directly contribute to solar energy adoption.', 'Highlight your experience building high-quality, scalable systems with Ruby on Rails and PostgreSQL, especially in fast-paced environments.', 'Show that you are a collaborative problem-solver who enjoys working with product teams to find high-leverage solutions.', 'Mention any experience with financial systems or automation, as the role involves loan servicing and solar value evaluation.']

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🔍 Research Before Applying

To stand out, make sure you've researched:

  • → Read about Wunder Capital's mission and their role in the solar financing space—understand how they differentiate from competitors.
  • → Familiarize yourself with the basics of solar project development and loan servicing to understand the domain.
  • → Check out Wunder Capital's engineering blog or any public talks to understand their tech stack and culture.
  • → Look into recent news or funding rounds to gauge the company's growth and stability.

💬 Prepare for These Interview Topics

Based on this role, you may be asked about:

1 Deep dive into your experience with Ruby on Rails: discuss specific projects, architectural decisions, and how you handled scaling.
2 How do you design and maintain CI/CD pipelines? Walk through a real example with CircleCI or similar.
3 How would you approach building a system to automate solar project evaluation? Consider data models, APIs, and performance.
4 Describe a time you collaborated with a product team to identify a high-impact solution. How did you balance technical debt vs. speed?
5 Why cleantech? Why Wunder Capital specifically? Be prepared to discuss your motivation and understanding of the solar industry.
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⚠️ Common Mistakes to Avoid

  • Don't submit a generic application—failing to mention cleantech or solar energy shows lack of genuine interest.
  • Avoid overemphasizing frontend or non-Rails experience; this role is primarily backend with Ruby on Rails.
  • Don't neglect to discuss testing and CI/CD—the job description specifically mentions well-tested code and rapid deployment.

📅 Application Timeline

This position is open until filled. However, we recommend applying as soon as possible as roles at mission-driven organizations tend to fill quickly.

Typical hiring timeline:

1

Application Review

1-2 weeks

2

Initial Screening

Phone call or written assessment

3

Interviews

1-2 rounds, usually virtual

✓

Offer

Congratulations!

Ready to Apply?

Good luck with your application to Wunder Capital!

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