Back-end Engineer, Trust & Safety

Eureka is the company behind "Pairs," a dating and matchmaking app for people who are serious about finding a partner. Pairs is one of Japan's largest online dating apps, with over 27 million cumulative registrations in Japan. Since launching the Japanese version in 2012, the Taiwan version in 2013, and the South Korea version in 2025, the service has continued to grow steadily, with over 700,000 people finding a partner through Pairs. In 2015, we joined Match Group, which operates online dating apps worldwide. To realize our mission of "creating things that people will be glad existed in their lives," we are aiming for further growth not only in Japan but globally.

Job Summary: The UTH (Under The Hood) Backend Team aims to lead the further growth of Pairs by building a robust and scalable foundation. This includes providing infrastructure for microservices and related components that support Pairs' core functionality, as well as improving application security, development productivity, and quality. This position is for a Backend Engineer who will work exclusively on the Trust & Safety project as a member of the UTH Backend Team. Specific responsibilities include continuously monitoring and analyzing data related to violating or malicious users, evaluating risks and impacts, and rapidly implementing and improving necessary countermeasures. You will also contribute to deterring malicious use and protecting users through the design, development, and operation of backend systems that support Trust & Safety tasks such as detection, prevention, investigation, and response. Additionally, you are expected to work closely with stakeholders in the Trust & Safety domain to continuously improve the accuracy of countermeasures and operational efficiency based on insights and data gained from the field. Through these efforts, you will contribute to creating an environment where users can use Pairs with peace of mind.

What You’ll Do:

• Design, apply, and operate mechanisms aimed at reducing risks such as violations, malicious use, and policy breaches in the Trust & Safety domain.
• Independently monitor and analyze data such as user behavior, system logs, and campaign results to evaluate risk signs, trends, the scale of issues, and the effectiveness of measures.
• Based on analysis and evaluation results, continuously improve the mechanisms supporting Trust & Safety tasks—such as detection, prevention, investigation, and response—to adapt to changing risk patterns.
• Collaborate with stakeholders in the Trust & Safety domain, Data Analysts, product backend teams, SRE teams, and security teams to contribute to deterring fraud and abuse, protecting users, and improving the reliability of Pairs while enhancing quality, performance, security, and operability.

Basic Qualifications:

• Strong motivation for improving development efficiency, performance, and security.
• Ownership and communication skills to effectively involve stakeholders and achieve results.
• Willingness to catch up on and learn about AI; experience developing with Coding Agents.
• 3+ years of experience in implementing, releasing, and operating commercial applications.
• Experience building commercial Web APIs running on Public Clouds such as AWS/Google Cloud.
• Experience in building and designing various testing methodologies.
• Experience in creating and operating commercial container images for web applications (e.g., Dockerfiles, installing necessary middleware).
• Basic knowledge of middleware commonly used in web applications, such as Nginx and MySQL.
• Japanese: Business level or higher; English: Conversational level or higher.

Preferred Qualifications:

• Experience in continuously improving detection, prevention, and response mechanisms by independently analyzing data such as user behavior, system logs, and campaign results in fast-changing risk areas like fraud, abuse, and policy violations.
• Ability to independently extract, aggregate, and analyze data to evaluate the scale of issues, priorities, the validity of measures to be implemented, and the effectiveness of measures, while receiving support from Data Analysts as needed.
• Experience in performing analysis and evaluation in environments where target user behavior and risk patterns change rapidly, and using those results to drive development and improvements.
• Experience and knowledge in designing databases and applications with scalability in mind, considering large-scale data and access volumes.
• Experience in working on development flows, code quality, documentation, and team productivity improvement using AI development support tools.
• Experience in building deployment scripts or Dockerfiles for applications in container environments.
• Experience or knowledge in building infrastructure on Public Clouds such as AWS/Google Cloud.
• Knowledge of basic security measures and their necessity in web applications.

Tools we use: Programming Languages: Go, TypeScript/JavaScript, Python

Tech Stack: MySQL,DynamoDB,Redis,Elasticsearch, Kubernetes,and various AWS and Google Cloud services,Terraform

Development: Git,Github,GithubActions,Docker,Jira Cloud,Slack

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