Senior Fullstack Engineer, Payments
alt • Remote
No Relocation
Posted: February 8, 2026
Job Description
We’re looking for a Senior Fullstack Engineer who wants to build the financial engine of our platform. You’re not just building a checkout flow; you’re powering the liquidity that makes this marketplace work. You’ll join a high-impact team responsible for our custom double-entry ledger, payment provider integrations, and our core lending products.
If you have a "measure twice, cut once" mindset for backend integrity but still move with a bias toward action on the frontend, you’ll thrive here.
What You’ll Do Here:
- Engineer Financial Integrity: Build and maintain our custom-built double-entry ledger system to ensure every cent is accounted for across the platform.
- Own Lending Infrastructure: Design and scale our lending products—from the logic of credit disbursements to the automated lifecycle of loan management.
- Architect Integrations: Design and implement robust integrations with payment gateways and banking partners, ensuring 99.99% reliability and seamless reconciliation.
- Own the UX of Money: Create high-trust user interfaces for payments and lending that make complex financial actions feel simple, transparent, and secure.
- Balance Rigor with Speed: Make thoughtful trade-offs between rapid feature shipping and the uncompromising correctness required for financial systems.
- Be a Multiplier: Level up the team through rigorous code reviews, technical documentation, and mentorship.
This is a perfect fit if you…
- Are Obsessed with Correctness: You understand that in payments, "mostly working" is a failure. You think deeply about idempotency, race conditions, and data consistency.
- Think Like a Product Owner: You don't just build a "pay button"; you understand the flow of funds and how to communicate financial status clearly to the user.
- Love Building Infrastructure: You’re energized by the challenge of building a ledger or a lending engine from the ground up.
- Are Pragmatic: You know when to build a custom internal solution and when to leverage a third-party API to get the job done.
What You Bring to the Table:
- 5+ years of experience with a heavy focus on backend systems (Python, Postgres, AWS) and a proven ability to build modern frontends (React, TypeScript).
- Fintech or Payments experience: You’ve worked with ledgers, payment processors, or lending products and understand the complexities of moving money.
- Database Mastery: You are an expert in SQL and relational database design—you know how to write a transaction that won't fail under load.
- Fullstack Ownership: A track record of taking a complex financial feature from a technical design doc all the way to a polished UI in production.
- Bonus: Experience with distributed systems, credit/risk modeling, or the alternative asset space.
What You’ll Get From Us:
- A seat at the table to help shape the future of Alt and the alternative asset space
- Autonomy and ownership on projects that matter
- $100/month work-from-home stipend
- $200/month wellness stipend
- WeWork office stipend
- 401(k) retirement benefits
- Flexible vacation policy
- Generous paid parental leave
- Competitive healthcare benefits, including HSA, for you and your dependent(s)
Base salary range: $140,000-$180,000, plus equity. Offers may vary based on experience, location, and other factors.
Additional Content
We’re looking for a Senior Fullstack Engineer who wants to build the financial engine of our platform. You’re not just building a checkout flow; you’re powering the liquidity that makes this marketplace work. You’ll join a high-impact team responsible for our custom double-entry ledger, payment provider integrations, and our core lending products.
If you have a "measure twice, cut once" mindset for backend integrity but still move with a bias toward action on the frontend, you’ll thrive here.
What You’ll Do Here:
- Engineer Financial Integrity: Build and maintain our custom-built double-entry ledger system to ensure every cent is accounted for across the platform.
- Own Lending Infrastructure: Design and scale our lending products—from the logic of credit disbursements to the automated lifecycle of loan management.
- Architect Integrations: Design and implement robust integrations with payment gateways and banking partners, ensuring 99.99% reliability and seamless reconciliation.
- Own the UX of Money: Create high-trust user interfaces for payments and lending that make complex financial actions feel simple, transparent, and secure.
- Balance Rigor with Speed: Make thoughtful trade-offs between rapid feature shipping and the uncompromising correctness required for financial systems.
- Be a Multiplier: Level up the team through rigorous code reviews, technical documentation, and mentorship.
This is a perfect fit if you…
- Are Obsessed with Correctness: You understand that in payments, "mostly working" is a failure. You think deeply about idempotency, race conditions, and data consistency.
- Think Like a Product Owner: You don't just build a "pay button"; you understand the flow of funds and how to communicate financial status clearly to the user.
- Love Building Infrastructure: You’re energized by the challenge of building a ledger or a lending engine from the ground up.
- Are Pragmatic: You know when to build a custom internal solution and when to leverage a third-party API to get the job done.
What You Bring to the Table:
- 5+ years of experience with a heavy focus on backend systems (Python, Postgres, AWS) and a proven ability to build modern frontends (React, TypeScript).
- Fintech or Payments experience: You’ve worked with ledgers, payment processors, or lending products and understand the complexities of moving money.
- Database Mastery: You are an expert in SQL and relational database design—you know how to write a transaction that won't fail under load.
- Fullstack Ownership: A track record of taking a complex financial feature from a technical design doc all the way to a polished UI in production.
- Bonus: Experience with distributed systems, credit/risk modeling, or the alternative asset space.
What You’ll Get From Us:
- A seat at the table to help shape the future of Alt and the alternative asset space
- Autonomy and ownership on projects that matter
- $100/month work-from-home stipend
- $200/month wellness stipend
- WeWork office stipend
- 401(k) retirement benefits
- Flexible vacation policy
- Generous paid parental leave
- Competitive healthcare benefits, including HSA, for you and your dependent(s)
Base salary range: $140,000-$180,000, plus equity. Offers may vary based on experience, location, and other factors.