Staff Backend Engineer

About the job

Castle is a profitable Series A startup on a mission to create a safer online world by protecting platforms from fraud, abuse, and malicious activity. Trusted by companies like Canva, Atlassian, and Rockstar Games, we’re backed by Y Combinator, Index Ventures, and top-tier angels from Datadog, Stripe, and New Relic. Our fast-moving team is scaling globally, helping platforms stay secure while thriving in a rapidly evolving digital landscape.

Every month, our systems process billions of API requests with strict latency requirements to enable real-time decision-making for our customers. In addition to solving cutting-edge scalability challenges, we strongly emphasize crafting exceptional user experiences and design.

This is a fully remote role, with teammates in the US, Poland, Portugal, Sweden, and France. We have a local presence in New York and Cracow if you prefer to come into the office. We expect candidates to be located in time zones between UTC-5 (New York) and UTC+1 (Cracow) to ensure smooth collaboration.

Responsibilities:

• You'll be working on our core platform and product, built on a modern stack including AWS Cloud, Ruby on Rails 7, and Angular 18.
• You'll collaborate closely with other team members, brainstorming ideas, providing constructive feedback, and reviewing their work to ensure high-quality outcomes.
• You'll ship incrementally and frequently, driving a constant flow of iterative, customer- and internal-feedback-driven development.
• As part of a small team, you'll have a significant impact on the direction and implementation of our projects, shaping the future of our product.

Qualifications:

• 6+ years of professional software development experience, ideally in a SaaS and/or startup environment.
• Experience building large-scale, performance-optimized production applications, preferably in Ruby, but proficiency in other similar languages, such as Node.js should enable a relatively straightforward transition.
• Experience shipping a public-facing API is highly valuable. You should be passionate about developer ergonomics, API design, and making our product as seamless and enjoyable to integrate with as possible.
• Strong verbal and written English communication skills to effectively collaborate with a distributed team and engage with customers when needed.

Cultural fit:

• At Castle, we foster a culture of innovation, collaboration, and ownership. If you enjoy working in a fast-paced, startup environment where you can make a real impact, you’ll thrive here.
• We believe in empowering individuals to take full ownership of their work, driving projects from concept to completion with autonomy and accountability.
• We value curiosity, adaptability, and a growth mindset. Whether you're experimenting with new ideas or iterating on existing solutions, we encourage open communication and constructive feedback.
• As a small team, we prioritize optimizing people’s efficiency and welcome the use of automation and AI-powered tools to enhance productivity.

Offer:

• Salary: $153k - $206k
• Flexible work hours. We prioritize outcomes over hours spent.
• Unlimited PTO. Take the time you need to recharge and maintain a healthy work-life balance.
• Paid parental leave. Supporting new parents during their transition.
• We’ll supply the computer and related gear you need to excel.