Systems Software Engineer (Intern)

Substrate builds financial infrastructure for equipment financing, a $1.3T market that still runs on manual approvals and paper. We give equipment vendors an in-house-bank capability: AI-powered underwriting, capital-as-a-service, and point-of-sale integrations. Our customers range from construction auctioneers and CNC distributors to robotics startups. We are a team of 10+ from Ramp, SpaceX, and Anthropic, backed by a $7M seed from Floodgate, Ironspring, Neo, and Steel Atlas.

We're hiring a systems software engineer intern who has tackled hard technical problems to help us build core 0→1 systems at the intersection of software, hardware, and finance. You'll help architect and ship systems that power machine shops, farms, factories, construction contractors, and more.

Substrate engineering interns have immense ownership to lead full-stack product cycles end-to-end, from customer discovery to production deployment. You'll get to occasionally travel with the founder to factory floors, meet Main Street manufacturers and Wall Street lenders face-to-face, and build exactly what the field demands.

Given the technical complexity of our product and the high degree of ownership we trust interns with, we've found engineers typically take 6-8 weeks to fully onboard and lead their own projects. Therefore, we require candidates who can commit to an internship for at least 8 months. We occasionally make exceptions for those who are truly exceptional.

• You believe in objective good and beauty, and you want to bring them to an antiquated, predatory industry.

• You believe not all technology is created equal. You don’t care about building another enterprise SaaS tool, you want to build tools that advance civilization.

• You want to work with people who treat their work as craft, who violently reject “just good enough,” and you want to help build that culture.

• Design and operate the backend for the loan lifecycle (application, underwriting, funding, servicing) in TypeScript on Node.js (NestJS services), PostgreSQL with Prisma migrations, and containers on AWS.

• Build asynchronous workflows with queues, retries, and recovery from partial failures related to payment collection and returns, daily loan-servicing jobs, bank-statement analysis, and credit and business-verification data ingestion.

• Model complex business workflows (credit policy, compliance checks, approvals) as explicit state machines with audit trails.

• Design and deploy production LLM and agentic systems that automate underwriting, compliance, and document processing, including evaluation and fallbacks.

• Own Postgres schema design, migrations, and query performance on production data.

• Extend our double-entry loan-servicing ledger: new transaction types and payment flows, guarded by database-level invariants and property-based tests.

• Integrate our systems with external financial partners: our bank partner for ACH origination, a bank-data aggregator, commercial credit bureaus, and business-verification providers.

• Experience building and operating production backend systems

• Production PostgreSQL experience: schema design, migrations, transactions, indexing, query performance.

• Can walk through the hardest system you've built in depth: stack chosen, alternatives rejected, key challenges, tradeoffs.

• Clear written and verbal communication: you turn ambiguous needs into working software and explain tradeoffs to product and design.

• You've solved hard technical problems most of your peers haven't encountered and you can explain exactly how your solution works to extreme depth

• You gravitate towards thinking in systems, infrastructure, and architectural tradeoffs

• You resonate with our engineering philosophy

• Proficiency in TypeScript or another typed backend language

• Built and shipped agentic workflows or automations

• AWS experience such as ECS on Fargate, Aurora PostgreSQL, S3 and CloudFront, Cognito, and Secrets Manager/KMS, managed with Terraform.

• Comfortable building React front ends.

If you are interested, please apply via Dover AND email [email protected], [email protected], and [email protected] with answers to the following (less than 3 sentences each):

• If you could have one person's career arc, who would it be and why?

• What's an unpopular truth you believe in?

• What's the most technically challenging system you've ever built? Include the tech stack you chose, why you chose them over other alternatives, key technical challenges and how you solved them, and any architectural tradeoffs you had to make.

• Link to Linkedin, Github, personal page, or anything relevant about you online.

• Resume (PDF)

• We require a minimum internship duration of 8 months. Please confirm your intended start date and internship length.
  

• We are headquartered in San Francisco and you are welcome to work with us in-person, however, this is not a requirement and you may work fully remote. Please share your intended work location, time zone you would work from, and confirm if you can overlap with at least 6 hours within 8am-5pm Pacific Time.