Senior Backend Engineer

The French Sourcer; San Francisco (CA); On-site; USD 170,000 - 230,000; Full time

Job summary

The French Sourcer is seeking a Senior Backend Engineer in San Francisco to own core backend systems powering payments and credit workflows. You will design APIs and data contracts used by data science and risk teams, and you’ll build internal tools to trace decisions without always pinging an engineer.

You’ll work with TypeScript in production, on a serverless AWS stack, and tackle reliability and latency challenges while shipping end-to-end solutions for live enterprise transactions.

Qualifications

• 5–12 years of backend engineering experience with production ownership.
• Strong hands-on experience with TypeScript in production.
• Experience in payments, fintech, or credit/risk systems.
• Comfort with AWS, serverless architecture, and designing for reliability at scale.

Responsibilities

• Own production backend systems powering core payments and credit workflows using TypeScript and Node.js.
• Design APIs, services, and data contracts used daily by risk, data science, and product teams.
• Build internal tools to review decisions and trace data lineage without engineering help.
• Turn ambiguous problems into shipped, production-grade components.

Skills

TypeScript

Node.js

SQL

AWS

Tools

AWS Lambda

PostgreSQL

Snowflake

Job description

Senior Backend Engineer — San Francisco

San Francisco, CA, United States · Permanent · On-site (5 days a week, flexible to 3 for exceptional profiles)

Own backend systems where a bug doesn't just break a feature, it touches real money moving through real credit decisions.

What you'd actually work on

• Building and owning production backend systems that power core payments and credit workflows, using TypeScript and Node.js end to end
• Designing APIs, services, and data contracts that other teams (data science, risk, product) depend on daily, where "good enough" stops being good enough once real transactions are on the line
• Building internal tools that let non-engineering teams review decisions and trace data lineage without pinging an engineer every time something looks off
• Taking ambiguous, loosely defined problems and turning them into shipped, production-grade slices rather than waiting for a fully scoped ticket
• Improving reliability and latency on systems where downtime or a bad edge case has a direct, visible cost, not just a Slack complaint
• Working cross-functionally with risk and data science to define what data actually needs to look like before it hits a decisioning model
• Owning the full lifecycle from architecture decisions through to production support, not handing off after the first deploy

Where it gets technically interesting

• A TypeScript and Node.js backend where correctness isn't optional. This stack directly powers payment and credit decisions, so tradeoffs get scrutinized differently than in a typical SaaS product
• Serverless architecture on AWS (Lambdas), which means thinking hard about cold starts, statelessness, and failure isolation rather than defaulting to a monolith
• A PostgreSQL data layer feeding into Snowflake for downstream analytics and modeling, so schema decisions have consequences well past your own service
• Designing systems and data contracts from close to zero: the infrastructure is still being defined, so you'll shape patterns other engineers will follow, not just extend someone else's
• Close, regular collaboration with a data science team turning your APIs and data pipelines into production, ML-driven decisions, which raises the bar on what "clean data" actually means
• Real production stakes from day one: the systems you touch are already live with paying enterprise customers, not waiting on a future launch

What we're looking for

• 5 to 12 years of backend engineering experience, including real production ownership, not just feature work inside someone else's system
• Strong hands‑on experience with TypeScript in production, plus solid SQL and relational database skills
• Direct experience in payments, fintech, or credit and risk systems, ideally at a fast‑growing, VC‑backed company
• Comfort with AWS, serverless architecture (Lambdas), and designing for reliability at scale
• A track record of owning a project or product area end to end: defining the problem, proposing the approach, shipping it, and iterating
• Experience collaborating across risk, data science, and engineering, not just within a single team's boundaries
• Bonus: Python proficiency and experience with data pipelines, ETL, or Snowflake

The companyAn AI-native fintech company building credit and payments infrastructure for B2B commerce, backed by top‑tier venture investors with $250M+ raised to date. A lean engineering team of around 30 to 40 people, already powering payment and credit workflows for enterprise customers in live production, not in beta. This role sits close to the founding team and works directly with risk and data science on some of the company's highest-stakes systems.

Compensation: $170,000 to $230,000 base, plus competitive equity

Languages: English (fluent, professional)