Mid-level Web Engineer

The Web Engineer works on freee’s Billing Core, the Lead-to-Cash platform for its multi-product SaaS business. As pricing expands from subscriptions to usage-based and hybrid models, the team evolves revenue infrastructure to support changing business needs. The role combines near-term capabilities with redesign of a high-traffic system carrying complex business logic. Work includes building campaign and plan features with business teams, tuning performance in the current Rails application, and creating self-service tools that automate contract and billing operations. The engineer will reshape contract, billing and invoicing domains and system boundaries, and modernize backend services with Go using an appropriate modular-monolith or microservices architecture. Transaction consistency and integrations with Zuora and Salesforce are also in scope. Requirements include experience designing, developing and operating web-application backends, and experience with either complex-domain modeling or database design. Applicants must have used AI tools such as Claude for development, professionally or personally, and put business-problem solving ahead of technology for its own sake.