Mercari, Inc.

Engineering Manager

• メルコインのプロダクトの開発と運用およびGrowth
• エンジニアの採用、育成、目標設定、評価、フィードバック
• エンジニアメンバーの成果の最大化とキャリア成長の支援
• 個人の成長と会社の状況を踏まえて、適切なアサイン
• エンジニアリング組織としての課題解決や成長戦略の提案と実行
• 専門性や組織理解を深める社内イベントの企画と実施

Risk

• リスク管理方針の企画・立案
• リスク管理に係る体制・規程の構築及び会議体運営
• リスクアセスメント、部門内外のステーク・ホルダーとのコーディネーション及び対応策の立案
• リスク低減策に関するモニタリング
• その他、リスク管理に関連する業務全般

Risk Management Specialist

Backend Engineer

• Lead the development of complex backend features and services, such as payment processing and inventory management systems
• Design and implement scalable backend architectures and patterns, including microservices and event-driven systems
• Drive technical decisions and best practices for backend development, including coding standards, performance budgets, and testing strategies
• Mentor and guide other engineers in backend development practices through code reviews and technical presentations
• Collaborate with product and frontend teams to define technical requirements and feasibility of new features
• Optimize backend performance and scalability, focusing on database optimization, caching strategies, and load balancing
• Contribute to backend platform technology and strategic roadmap decisions, including technology evaluation and technical debt reduction
• Lead technical discussions and architectural reviews for major features and system changes

Senior Software Engineer, Backend

Customer Success Manager

• フリマアプリ「メルカリ」ないし、同アプリで展開されるメルペイやメルコインといったプロダクトをより良い体験でご利用いただくためのCRMに関するプロジェクト推進、具体的なCRMの企画・管理をチームのミッションに基づきながら実施していただきます。
• グループの施策が多数走る中で、CRMに関する課題解決のコンセプト策定、戦略立案、そして実行。それらを一気通貫で自走していただくことはもちろん、プロジェクトチームを牽引し、成功に導いていただきます。
• 大きな期待を受けるポジションでありますが、その分ほかにない経験とスキルを得られ、社会に大きなインパクトを与えることができます。
• おもなプロジェクト領域は下記の通りです。
• 全社横断でのCRM周りの課題解決
• AIを活用した全社CRM推進
• お客さまコミュニケーションの体験管理

Senior CRM Specialist

Digital Marketing

• Plan, launch, and optimize digital advertising campaigns across major paid channels (Google Ads, Meta, TikTok, YouTube, and others) to acquire new users and grow engagement in the US market.
• Develop and manage performance marketing strategies that balance acquisition volume, efficiency, and quality of users.
• Continuously monitor campaign data, analyze KPIs, and apply insights to improve conversion rates and ROI.
• Collaborate cross-functionally with creative, analytics, and product teams to align campaign strategies with overall business goals.
• Localize and tailor ad creatives and messaging for the US audience, ensuring cultural and linguistic relevance.
• Manage budgets and pacing, ensuring optimal use of spend across channels.
• Conduct A/B tests to identify the most effective targeting, bidding, and creative strategies.
• Report and present campaign performance, insights, and recommendations to stakeholders.
• Establish local connections and facilitate effective communication.
• Plan and execute comprehensive growth initiatives in the US beyond Paid Ads.

Global Digital Marketing Specialist

Security Engineer

• Participate in threat modeling, code reviews, and security testing under the guidance of senior engineers to help identify and reduce risk in Mercari’s systems.
• Develop or enhance automation scripts for common security tasks such as compliance checks, asset inventory reconciliation, and alerting.
• Conduct focused security research on a supervised topic (e.g., AI system security, supply chain risks), summarize key findings, and propose actionable improvements for Mercari.
• Support vulnerability management processes by helping triage security findings, verify issues, and coordinate with developers on remediation efforts.
• Contribute to internal documentation, including secure development guidelines, AI security best practices, security playbooks, and onboarding material for engineers.
• Assist in security monitoring efforts, such as analyzing logs to detect anomalies, tuning detection rules, and helping track misconfigurations or policy violations.

Security Engineer, Internship

Technical Program Manager

• Lead critical AI initiatives as a Technical Program Manager on the AI Taskforce.
• Drive creation of a foundational Generative AI platform by integrating best-in-class services for product teams.
• Manage programs to improve internal engineering productivity using AI across Mercari’s SDLC.
• Serve as central coordinator for AI strategy, ensuring timely delivery of complex projects.
• Manage full lifecycle of GenAI integrations from prototyping to full-scale deployment and iteration.
• Partner with engineering and product leaders to define AI platform roadmaps for standardized, secure, scalable infrastructure.
• Act as liaison between AI Taskforce and internal teams to drive adoption of AI capabilities.
• Lead operational governance programs for compliance, security, and ethical AI frameworks.
• Develop enablement and adoption programs, including training, APIs, documentation, and support channels.
• Identify and mitigate risks related to model performance, cost, data security, and vendor dependencies

AI Engineer

• Design, develop, and deploy innovative AI applications using foundation models (LLMs, Multimodal Models) across Mercari.
• Build foundational platforms and services enabling product teams to ship scalable AI features.
• Build Foundational AI Services using prompt engineering, RAG, and fine-tuning to solve high-impact problems.
• Collaborate with product, engineering, and infrastructure teams to integrate AI into the Mercari app and architect modular scalable solutions.
• Develop evaluation pipelines to measure, monitor, and improve model performance focusing on accuracy, latency, cost, and responsible AI.
• Own features end-to-end: problem scoping, prototyping, production deployment, maintenance, and iteration based on metrics and user feedback.
• Stay at the forefront of AI engineering advancements and share knowledge to uplift organization capabilities.

Technical Product Manager

• Responsible for a wide range of product management tasks in Mercari Group's Trust & Safety area (fraud/abuse prevention, financial crime prevention)
• Use products to address unauthorized logins, fraudulent payments, and fraudulent listings
• Improve existing features and participate in internal fraud prevention projects
• Formulate mid-term strategies for TnS products and implement current product tasks and improve fraud monitoring operations
• Own the vision, roadmap, and delivery for the internal Tool powering reports, escalations, and moderation
• Partner with Engineering, Design, CS, TnS and related teams to build scalable internal tools
• Translate operational needs into clear product requirements and user stories
• Define KPIs, run experiments, and use data to guide decisions
• Ensure features support risk detection, abuse prevention, and regulatory compliance
• Bridge communication between Japan-based teams and global stakeholders

Technical Product Manager, Japanese Bilingual

Machine Learning Engineer

• Lead the end-to-end ML model lifecycle: identify machine learning opportunities through data and metric analysis, define and track KPIs, and ship iterations aligned with product and business goals.
• Design, develop, and maintain ML pipelines, including feature engineering, model training, deployment, and monitoring.
• Implement scalable inference services and APIs for real-time and batch predictions.
• Improve model accuracy, inference speed, and robustness through experimentation, hyperparameter tuning, and feature optimization.
• Ensure reliability through comprehensive automated testing, observability, and reproducibility of ML experiments.
• Mentor junior engineers, lead code and model reviews, and contribute to architectural decisions and technical documentation.
• Collaborate with cross-functional teams across product, engineering, and operations and with teams in the US and Japan to deliver high-impact ML solutions at global scale.
• Architect and operate highly scalable ML services and pipelines to support rapid user and product growth in the US market.
• Leverage large language models (LLMs) and generative AI to enhance search recall, content understanding, and overall user experience.
• Optimize experimentation frameworks to accelerate product iteration and innovation.

Software Engineer, Machine Learning

Data Analyst

• 就業型インターンとして現場のプロジェクトに配属され、チームの一員として業務を担当
• データ分析によってメルカリのプロダクト改善機会を発見・提案
• マーケティングの効果最大化のための分析業務
• メルカリグループ横断での経営意思決定を支援するための分析とインサイト提供
• 大量の行動ログや取引データを用いた実務的な分析業務に携わる
• 社内の各部署と協働し、施策検証やKPI設計、モデル構築などを行う
• 分析結果や考察をわかりやすく社内に伝達し、意思決定をサポートする

Data Analyst / データアナリスト – Internship

Producer

• メルカリグループのミッション・バリューを深く理解し、Webサイトを通じたブランドコミュニケーションを主導する
• ブランド戦略に基づいたWebサイトの企画・ディレクションを行う（各タッチポイントのデザインやメッセージ整理、サイト横断のシームレスな体験設計）
• コーポレートサイトの管理オーナーとして、予算管理、運用更新、品質管理などの定常業務を遂行する
• データやユーザー行動に基づいたコミュニケーション・デザイン施策のプランニングやディレクションを実施する（Google Analytics、A/Bテスト等を活用）
• コーポレートサイト、採用サイト、SDGsサイトなどの運用・リニューアルおよびブランドサイトや新規タッチポイントのコンセプト設計・制作ディレクションに携わる

Web Director / Producer

Customer Support

• Social Support主要業務に対する四半期毎のKPI推進・達成
• 社内外とのミーティングへの参加、ファシリテート
• 5人以上のチームメンバーの生産性・品質のリード
• 障害発生時の社内外のコミュニケーション対応
• オペレーションに関するリスクアセスメントの実施
• オペレーションの現場に入り込んだ運用課題の特定と改善
• オペレーションに関するプロジェクトの管理と推進
• 開発部門、Marketing、PR、法務などと協業してカスタマー体験の向上を検討・実行