Senior Full-stack Engineer – Agentic Payments

Crossmint

Senior Full-stack Engineer developing the infrastructure for AI agents to transact autonomously. Your work will shape the future of programmable finance at Crossmint with scalable systems.

Posted 6/20/2026full-timeNew York City • Florida, New York • 🇺🇸 United StatesSenior💰 $200,000 - $230,000 per yearWebsite

Tech Stack

Tools & technologies

JavaJavaScriptPythonRuby on RailsTypeScript

About the role

Key responsibilities & impact

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.

Requirements

What you’ll need

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.

Benefits

Comp & perks

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.

ATS Keywords

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Applicant Tracking System Keywords

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Hard Skills & Tools

TypeScriptJavaScriptJavaPythonproduction systemsbackend developmentfull-stack developmentpayment flowstokenizationsmart contracts

Soft Skills

strong communication skillsmentoringownership mindsetproduct mindsetbalancing usability and securitytechnical bar raising

Certifications

Bachelor's degree in Computer Science