Eureka operates "Pairs," a dating and matchmaking app for those seriously looking to find a partner. Pairs is Japan's largest online dating app with over 27 million cumulative registrations in Japan. Since launching the Japanese version in 2012, the Taiwan version in 2013, and the Korean version in 2025, it has continued to grow steadily, with over 700,000 people finding their partners on Pairs. In 2015, we joined Match Group, which operates online dating apps worldwide. To realize our mission of "creating something that makes people grateful to have in their lives," we are pursuing further growth not only domestically in Japan but also globally.
Job Summary: The UTH (Under The Hood) Backend Team supports feature development for the Pairs platform by providing microservices and related component infrastructure, and by improving application security, development productivity, and quality. Through these efforts, we build a robust and scalable foundation to drive Pairs' continued growth. This position is a Backend Engineer role dedicated to the Trust & Safety project as a member of the UTH Backend Team. Specific responsibilities include continuously monitoring and analyzing data related to violating and malicious users, evaluating risks and impacts, and rapidly implementing and improving necessary countermeasures. Additionally, through the design, development, and operation of backend systems that support Trust & Safety operations—including detection, prevention, investigation, and response—you will contribute to deterring malicious use and protecting users. You are also expected to work closely with stakeholders in the Trust & Safety domain and continuously improve the accuracy and operational efficiency of countermeasures based on insights and data obtained from the field. Through these efforts, you will contribute to creating an environment where users can use Pairs with confidence.
What You'll Do: ・Design and implement mechanisms to reduce risks such as violations, malicious use, and policy breaches in the Trust & Safety domain, apply them to Pairs, and operate them ・Independently monitor and analyze user behavior, system logs, and initiative results to evaluate risk indicators, trends, the scale of issues, and the effectiveness of initiatives ・Based on analysis and evaluation results, continuously improve mechanisms supporting Trust & Safety operations—including detection, prevention, investigation, and response—to adapt to changing risk patterns ・Collaborate with Trust & Safety stakeholders, Data Analysts, product backend teams, SRE teams, security teams, and others to enhance quality, performance, security, and operability while contributing to fraud prevention, user protection, and improved trust in Pairs
Basic Qualifications: ・Strong motivation to improve development efficiency, performance, and respond to security issues
・Ownership and communication skills to effectively engage stakeholders and achieve results
・Willingness to learn about AI and experience developing with Coding Agents
・3+ years of experience implementing, releasing, and operating commercial applications
・Experience building commercial Web APIs running on Public Cloud platforms such as AWS/Google Cloud
・Experience designing and building various testing methodologies
・Experience creating and operating commercial container images for web applications (including dockerfiles and necessary middleware installation)
・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 rapidly changing risk domains such as fraud, abuse, and policy violations, where you independently analyzed user behavior, system logs, and initiative results, evaluated risk indicators, trends, and initiative effectiveness, and continuously improved detection, prevention, and response mechanisms
・Ability to independently extract, aggregate, and analyze data within a certain scope with support from Data Analysts as needed, and evaluate the scale of issues, priorities, the appropriateness of countermeasures to implement, and the effectiveness of initiatives
・Experience in environments where target user behavior and risk patterns change continuously over short periods, where you independently conducted analysis and evaluation and connected the results to development and improvements
・Design experience and knowledge of scalable databases and applications considering large-scale data and access volumes
・Experience working with AI development support tools to improve development workflows, code quality, documentation creation, and team productivity
・Experience building deployment scripts and dockerfiles for applications in container environments
・Experience or knowledge of infrastructure construction on Public Cloud platforms 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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