Software Engineer, Billing

Braintrust•Seattle, WA

10d

About The Position

Braintrust is hiring a Software Engineer, Billing to build systems that make its pricing, usage, and payments accurate, scalable, and transparent. The role supports a platform used to observe, evaluate, and improve production AI agents, where customer activity includes trace processing, automated and human evaluations, AI-powered product features, and data retention under different plans and policies. Billing systems must translate this activity into reliable customer experiences, including usage measurement, plan enforcement, invoices, credits, and account state. This is a deeply technical individual-contributor role focused specifically on billing architecture and systems, rather than finance operations or occasional billing work as part of a general backend role. The engineer will own and evolve systems spanning usage metering, subscriptions and entitlements, payment integrations, invoicing, credits, and reconciliation, and will help Braintrust introduce pricing models that support customers as their AI workloads grow.

Requirements

Expert-level understanding of TypeScript, Rust, SQL, backend systems, APIs, and distributed data-processing patterns.
Experience building and operating production usage-based billing, payments, or subscription systems.
Experience with metering, aggregation, idempotency, reconciliation, and event-driven architectures.
Experience integrating with Stripe or similar payment infrastructure.
Comfort shipping end-to-end, from backend infrastructure and data systems to internal tools and customer-facing UI.
Appreciation for balancing fast execution with customer trust and billing correctness.

Nice To Haves

Experience building or maintaining financial ledgers, credits, balances, or invoice systems.
Previous experience founding or working at startups.

Responsibilities

Own Braintrust’s billing architecture end-to-end, including metering, plans, subscriptions, entitlements, invoices, credits, and payments.
Design billing architecture that addresses immediate needs and simplifies billing for new features as they are developed and released.
Ensure accurate measurement and billing of product usage, including processed data, evaluation scores, model usage, and data retention.
Partner with product, infrastructure, finance, and customer-facing teams to introduce pricing models and billing workflows.
Build a reliable usage-metering and aggregation pipeline that converts product activity into accurate customer usage.
Build subscription, limits, and entitlement systems supporting plan allowances, feature access, trials, upgrades, and on-demand usage.
Build internal tools and APIs for investigating billing anomalies, issuing credits, and helping customers understand account state.
Provide observability across the billing pipeline, including metering lag, event completeness, reconciliation discrepancies, and payment health.