Senior Full-stack Engineer - Agentic Payments (NYC / MIA)

About Crossmint Global financial rails are undergoing a once-in-a-generation transformation. Instant settlement. Programmable. Agent-first. Crossmint is the infrastructure helping companies build for that future. We are the leading all-in-one stablecoin and wallet infrastructure platform, enabling fintechs, enterprises, and agentic platforms to integrate stablecoin rails with speed, compliance, and scale. Crossmint provides everything enterprises need to ship smart financial rails, including smart wallets, cross-chain stablecoin orchestration, on/offramps, token checkout, and more, all through a single developer-friendly API. Trusted by more than 40,000 clients including global leaders like MoneyGram, Western Union, and Paga to nation states like the Marshall Islands, Crossmint powers stablecoin flows that move billions from cross-border remittances, global payroll, to the world's first digital UBI program. MiCA-authorized, PSD2-licensed, and SOC2 Type II certified, Crossmint serves 150+ countries globally across 50+ blockchains. Backed by Ribbit Capital, Franklin Templeton, NYCA, First Round, and Lightspeed Faction. We're building the infrastructure for the era of programmable finance. Join us! Location NYC (preferred) or Miami. Hybrid office setting. Type of employment Full-time Salary range Senior level: 200,000 – 230,000 USD Note: Final level and compensation are determined during the interview process based on experience and fit. Seniority 7+ years building production systems, with a strong backend and full-stack track record. About The Role As a Senior Full-stack Engineer on the Agentic Payments Team, you will build and scale the infrastructure that lets AI agents transact safely and autonomously including the agent wallets, delegated authorization, checkout, and card rails that enterprises and developers use to give their agents real spending power. Your work will directly impact how companies let agents hold funds, make purchases, and pay for services strictly within the guardrails their users define. You'll build our offering across stablecoin rails and the major card networks' agentic programs, including Visa Intelligent Commerce, Mastercard Agent Pay, and more. You will ship enterprise-grade, production-ready services that developers integrate in minutes through secure APIs and SDKs. Responsibilities You will: Write high-quality production code that is correct, secure, performant, and maintainable. Build and scale agent wallet infrastructure: provisioning, signing flows, transaction orchestration, and lifecycle management for wallets owned and operated by AI agents. Design and enforce delegated authorization and programmable guardrails for spending limits, merchant allowlists, human-in-the-loop approval thresholds, and auditable transaction logs that let agents act autonomously within defined boundaries. Integrate agentic card rails, including Visa Intelligent Commerce, Mastercard Agent Pay, and emerging agent payment programs covering virtual card issuance, tokenization, and lifecycle. Build agent commerce and checkout experiences, from conversational checkout to programmatic purchasing, exposed through clean APIs and SDKs. Design scalable, secure systems that bridge agents, card networks, and onchain/offchain components while maintaining data integrity and compliance. Contribute to architecture and design documentation to shape the long-term evolution of Crossmint's agentic payments products. Own features end to end from design to production deploy and iteration. Participate in paid on-call rotations once or twice per quarter. Mentor and support teammates and help raise the technical bar across the engineering organization. About You To thrive in this role, you should have: Strong communication skills in written and spoken English. Bachelor's degree in Computer Science or equivalent professional experience. 7+ years building production systems, with a strong backend and full-stack track record. Strong programming skills in at least one modern language such as TypeScript (ideal), JavaScript, Java, Python, or similar. Experience with payments, card issuing/processing, transaction systems, or wallet/agent infrastructure. Solid understanding of payment flows — authorization, settlement, and tokenization — and/or blockchain fundamentals such as smart contract interactions, gas abstraction, and transaction lifecycles. You are opinionated about how to make endpoints and interfaces usable and ergonomic for agents as first-class users, and how to engineer modern AI-first systems and workflows. A product and ownership mindset with an ability to balance usability, security, and long-term reliability. A track record of owning complex systems end to end and mentoring other engineers. Strong Plus If You Have: Familiarity with agentic payment protocols and standards (x402, AP2/A2A, ACP) and/or card-network agent programs (Visa Intelligent Commerce, Mastercard Agent Pay). Experience with card issuing/processing, PCI-scoped systems, or payment orchestration at scale. Familiarity with EVM ecosystems, Solana, Stellar, or multi-chain stablecoin payments. Built and published skills, CLIs or MCP tools or have contributed to notable agentic harnesses or AI surfaces. Prior experience at a crypto-native, Web3, fintech, or payments engineering team. Compensation & Benefits Extensive access to leading AI tools and subscriptions, with AI actively encouraged and integrated into daily workflows. We conduct two performance reviews annually. The first addresses performance ratings, bonuses, and promotions. The second encompasses these elements along with salary adjustments reflecting inflation and market conditions. Stock options are part of every full-time offer. We want everyone here to be a genuine stakeholder in what we're building. Unlimited, flexible PTO. Parental Leave program. Flexible work schedule. Company laptop and allowance for any necessary home equipment. Daily stipend for commuting to the office and/or meals. Three company-paid off-sites per year. Health, dental, vision, life, short-term disability (STD), and long-term disability (LTD) insurances. 401(k) Plan. Our Principles Results and delivery: Ship high quality work fast. Build for the long term: Build scalable, secure, and reliable solutions. Use AI. Extreme Ownership: Be an effective Directly Responsible Individual (DRI). Be proactive. Be a team player: Be an effective and kind colleague providing credible challenge. Be present and reliable. Talent research indicates that women are often less inclined than men to apply for a role unless they have experience in 100% of the listed skills. However, this list is only a guide. We welcome your application even if you feel you meet around 75% of the requirements. At Crossmint, we believe skills can be learned, and diversity makes us stronger. We work to foster a respectful environment where each person can be their authentic self, free from harassment, racism, and any form of discrimination. We proudly uphold our commitment to diversity and inclusion as an equal opportunity employer, and this policy applies to all employment practices within our organization. Please note that Crossmint never conducts AI-based interviews, and all of our processes include an initial video call with a team member. Crossmint will not request your personal identification documents or any payment at any point during your interview process. Please stay vigilant about potential fraud. If you receive an email that claims to be from Crossmint but ends with any domain other than @crossmint.com, @crossmint.io or @paella.dev, it is not from us. We own these three domains listed before, and they are the only legitimate ones. Please let our Talent Team know if you need any assistance completing any forms, or participating in the process. Who will be in contact with you Our People Ops team will be joining you throughout the entirety of the interview and onboarding processes. Feel free to reach out if you need anything! Adolfo Fernández - Head of People Ops Gloria Alogo - People Ops, Onboarding & Benefits ⚠️ Please note that these are the only members of our People Ops team. Please remain vigilant and watch out for impersonators. Follow us on Linkedin and X to keep updated with our latest activity!