Backend Engineer

About Tokenz

Tokenz is a Merchant of Record for businesses selling digital goods. We handle checkout, payments, tax, compliance, subscriptions, and the infrastructure behind them so our customers can focus on building their products. Our platform gives merchants access to more than 100 payment methods globally without taking on the tax, accounting, and compliance burden themselves.

We recently raised our Series A and are growing our engineering team. We’re looking for a Senior Backend Engineer who enjoys understanding complex domains, making thoughtful technical decisions, and owning work from product requirements through production.

About the role

You’ll work across our backend, building features and systems where correctness has real consequences. Recent and ongoing projects include subscriptions, one-click purchases, payment-provider fallbacks, redemption codes, consumer dashboards, and merchant tooling.

Our backend is a JVM-based monolith built with Scala and ZIO. Prior Scala or ZIO experience is not required, but experience with typed backend systems and asynchronous programming provides a strong foundation for learning our stack.

As a senior engineer, you’ll take a product requirements document, clarify the domain and constraints, evaluate trade-offs, and deliver production-quality software. You’ll have meaningful ownership and support from teammates with payments experience. We pair on projects, including at the senior level, to share context and work through difficult decisions.

Main responsibilities

• Own features end to end. Work closely with product and frontend engineers to shape requirements, design solutions, implement them, and support them in production.
• Model complex business domains. Design schemas and data access patterns with attention to indexing, auditability, transactional workloads, analytics, and future consumers.
• Design APIs around complete user journeys. Define clear failure behavior, recovery paths, and idempotency where needed, while leaving room for future changes.
• Build reliable financial and operational flows. Work on money movement, exchange rates, payout ledgers, webhooks, subscriptions, and entitlements.
• Make practical reliability decisions. Reason about consistency, retries, synchronous versus asynchronous work, and dependencies on external systems that can fail.
• Operate what you ship. Investigate production issues, use logs and dashboards to understand behavior, participate in shared on-call, and improve systems after incidents.
• Contribute sound engineering judgment. Explain trade-offs, review designs and code, and adapt your approach as new information emerges.

What we’re looking for

• Experience building and shipping production backend systems, with end-to-end ownership of substantial features or projects.
• The ability to turn product requirements into a sound technical design and carry it through implementation and production delivery.
• Strong judgment in systems that depend on external services, including failure handling, idempotency, consistency, retries, and operational cost.
• Experience in a domain where correctness or coordination with unreliable external systems matters-for example, payments, commerce, bookings, logistics, messaging, or fintech.
• Production experience with a typed backend language such as Scala, Kotlin, Rust, TypeScript, Go, or modern Java, or comparable backend experience.
• A solid understanding of SQL, relational data modeling, and indexing. PostgreSQL experience is a plus.
• Confidence debugging and operating production systems.
• A pragmatic, collaborative approach: you ask good questions, choose designs that fit the problem, and revise your thinking when constraints change.
• Fluent written and spoken English.

Helpful, but not required

• Scala or functional programming experience.
• Experience with ZIO, Cats Effect, Effect-TS, or another effect system.
• Knowledge of Merchant of Record businesses, payments, subscriptions, fintech, tax, or compliance.

How we work

We’re one backend team working closely with product and frontend. We move quickly and take care with decisions that affect correctness, compliance, and customer trust. Engineers work across the product and build domain knowledge together.

On-call is shared across the team. Incidents are infrequent, but responding to production issues and learning from them is part of the role.

Location: Tokyo hybrid, with approximately two days per week in the office in Kamiyacho, or remote from time zones between Central European Time (CET/CEST) and Japan Standard Time (JST).

Working language: English.