Senior Backend Engineer - Payments & Fintech

PortugalRemoteFull-timesenior

OtherSenior Backend Engineer

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Quick Summary

Overview

This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Senior Backend Engineer - Payments & Fintech based in Portugal.

Technical Tools

OtherSenior Backend Engineer

This is a high-impact backend engineering role focused on rebuilding and scaling the financial systems at the heart of a rapidly growing global platform.
You will own the architecture and implementation of a canonical payments, subscriptions, billing, and entitlement platform from the ground up.
The role combines deep backend engineering with complex financial workflows spanning multiple payment gateways, legal entities, and currencies.
You will work closely with Finance, Operations, and technical leadership to ensure every payment, entitlement, refund, and financial record is accurate and traceable.
Your work will directly improve revenue integrity, accounting accuracy, customer entitlements, and business reporting.
You will also lead a careful migration from legacy systems to a reliable, auditable platform without disrupting live customers or financial operations.
This is an ideal opportunity for an experienced engineer who enjoys solving complex money-system problems where correctness, reliability, and data integrity are critical.

Design and implement a canonical billing and entitlement ledger using an append-only, journals-as-truth architecture and PostgreSQL, ensuring every entitlement can be traced to a valid paid order.
Own the complete subscription lifecycle, including purchases, renewals, resubscriptions, upgrades, downgrades, plan changes, trials, cancellations, lapses, proration, and dunning across multiple payment gateways.
Build reliable payment gateway ingestion pipelines with idempotent and replay-safe webhook processing, normalization, dead-letter handling, and daily reconciliation between gateway records and internal books.
Implement robust handling of refunds, chargebacks, disputes, credits, and partial or zero-value settlements while preventing double counting and ensuring accurate allocation of payment amounts.
Create trustworthy financial and entitlement data pipelines supporting accounting close, revenue recognition, indirect tax requirements, exchange reporting, and conversion and retention analytics.
Own the customer-facing billing experience, including checkout and account management functionality, ensuring the frontend experience remains fully aligned with the underlying financial ledger.
Lead the migration of the live business from legacy account and billing models, including historical data backfills, parallel operation, reconciliation, validation, and controlled regional cutovers.
Establish engineering practices that prioritize financial correctness, auditability, observability, reliability, and safe operation under concurrency and scale.

Requirements

~2 min read

6–10 years of backend engineering experience, with deep expertise in Go and strong relational database design and SQL skills.
Proven experience building or rebuilding payment, subscription, billing, and ledger systems end-to-end, including gateway integrations, idempotent webhooks, renewals, upgrades, proration, cancellation, dunning, refunds, and disputes.
Strong understanding of financial systems surrounding payment ledgers, including reconciliation, revenue recognition, taxation, financial reporting, and append-only or event-sourced ledger architectures.
Experience designing systems where derived state is based on authoritative financial records and where transactions must remain accurate and auditable under concurrency.
Background working on B2B products involving complex billing, metering, plans, add-ons, multi-tenant environments, or partner billing.
Advanced SQL skills and the ability to independently investigate financial discrepancies and trace issues directly through underlying data.
Working knowledge of TypeScript, React, and modern frontend development, with the ability to build and maintain customer-facing billing and checkout experiences.
Experience with multi-entity, multi-currency, or international billing is highly valuable, including familiarity with EU VAT/OSS, GST/IGST, or comparable tax frameworks.
Experience with AWS Cognito, identity systems at scale, legacy data migrations, financial reconciliation, finance-close workflows, or trusted revenue-reporting pipelines is a plus.
Fintech or trading-industry experience is advantageous but not essential; strong payments and billing expertise is the priority.
Strong ownership, analytical thinking, attention to detail, and communication skills, with the ability to collaborate closely with finance, operations, and technical leadership.
Comfortable working in a fast-paced environment where financial correctness and system reliability have a direct impact on the business.