Security Engineer - AppSec

About the Company Rain is the global stablecoin payments platform for enterprises, neobanks, platforms, developers, and AI agents. Our technology allows partners to move, store, and use stablecoins instantly and compliantly through global payment cards, rewards, on/offramps, wallets, and cross-border rails. As both a Visa and Mastercard Principal Member, Rain issues cards that work at more than 175 million merchant locations in over 220 countries and territories. Built natively for stablecoins and trusted by more than 100 organizations worldwide, Rain delivers secure, scalable infrastructure that makes money move freely and instantly around the world. You will have the opportunity to deliver massive impact at a hypergrowth company backed by some of the top investors in fintech, crypto, and SaaS. In January 2026, we closed a $250M Series C led by ICONIQ, valuing Rain at $1.95B, with Sapphire Ventures, Dragonfly, Bessemer Venture Partners, Galaxy Ventures, FirstMark, Lightspeed, Norwest, and Endeavor Catalyst also participating. If you're curious, bold, and excited to help shape a borderless financial future, we'd love to talk. Our Ethos We believe in an open and flat structure. You will be able to grow into the role that most aligns with your goals. Our team members at all levels have the freedom to explore ideas and impact the roadmap and vision of our company. About the Team Security Engineering is a small team that answers one question: was it built right? We run our own AI-driven red team against Rain's code and cloud, gate pull requests before they merge, and write the baselines that say how every system should be configured. Our blockchain work is covered. This role owns everything else: the backend services, APIs, cloud, and edge that move real money for real customers. We work closely with Security Operations: we give them high-quality findings to coordinate fixes for, and clear configuration rules they can build detections on. About the Team Security Engineering makes sure Rain is built right. We run our own AI-driven red team against our code and cloud, gate pull requests before they merge, and set the baselines for how every system is configured. This role owns everything outside blockchain: the backend services, APIs, cloud, and edge that move real money. We give Security Operations high-quality findings to coordinate fixes for, and clear configuration rules to build detections on. About the Role You'll be Rain's application security expert and the quality bar for every non-chain finding we produce. The calls are yours: what's real, how bad it is, and what has to be fixed before launch. You'll hold the line with engineers when it matters, and make the case so they agree, not just comply. What You'll Do Review red team findings before they reach engineers: reproduce them, cut false positives, set severity, and write tickets clear enough to fix without a meeting. Improve the scoring that grades them Harden our backend services and APIs, especially the money-moving paths. You'll often write the fix yourself Own edge defenses: DDoS protection, rate limiting, WAF rules, and abuse controls Write secure configuration baselines for our cloud, code, and SaaS, and turn them into automated checks Grow our PR security gate so more bugs are blocked before merge Own attack surface coverage, and run architecture reviews on new and high-risk systems Find, test, and pick the best security tools, whether we buy, adopt, or build What We're Looking For 4+ years in application security, product security, or security-minded backend engineering You've owned security decisions. You can tell a senior engineer their design needs to change and keep a good working relationship You can read an unfamiliar codebase (TypeScript/Node.js) and find the bug that matters, and you know a scary-sounding finding from a real one Hands-on cloud security (ideally GCP), Terraform, and edge defenses like WAFs and rate limiting Experience with threat models or architecture reviews. You've run tool bake-offs and dropped tools that didn't earn their cost You'd rather ship a check than write a document, and you use AI tools heavily without trusting them blindly Bonus Attributes Fintech, payments, or card issuing background (PCI DSS a plus) Pentest, bug bounty, or red team experience Experience building security scanners, static analysis rules, or LLM-based review tools If you have the background: AI security for our agents and agentic payments, or corporate security alongside IT Things that enable a fulfilling, healthy and happy experience at Rain: Unlimited time off 🌴 Unlimited vacation can be daunting, so we require Rainmakers to take 10 days minimum for themselves. Flexible working ☕ We support a flexible workplace – work from home, come into an office, or both. We want everyone to work in an environment where they're their most confident and productive selves. New Rainmakers receive a stipend to set up a comfortable home workspace. Easy to access benefits 🧠 For US Rainmakers, we cover 95% of your health, dental, and vision plan costs and 90% for your dependents, plus a 100% company-subsidized life insurance plan. Retirement goals 💡 Plan for the future with confidence. We offer a 401(k) with a 4% company match. Equity plan 📦 Every Rainmaker gets an equity option plan so we all benefit from our success. Health and Wellness 📚 High performance begins from within. Rainmakers receive a monthly stipend to be used for eligible health and wellness spending like gym memberships/fitness classes, massages, acupuncture - whatever recharges you! In-office meals 🍜 Rainmakers working from the office enjoy lunch and dinner on us, covered with a DoorDash credit. Team summits ✨ Summits play an important role at Rain. Time together helps us build relationships and a common destiny. Expect team and company offsites, both domestic and international.