Shinjuku-ku, Tokyo W3Global

Job Description
Senior Backend Engineer-SaaS Platform

Employment Type:
Full-time

Location:
Tokyo (Hybrid - 3 days office / 2 days remote)

Salary:
¥8M - ¥15M / year (plus overtime, bonuses, and stock options)

About The Company
A Japan-based marketing technology company operating globally in SaaS and AI solutions. The organization has been recognized among Asia-Pacific's high-growth tech companies and continues to scale its enterprise offerings through AI-powered business platforms.

The Role
As a
Senior Backend Engineer
, you will play a key technical leadership role in developing and scaling a fast-growing
SFA/CRM SaaS product
. This position focuses on backend architecture, team mentorship, and code quality improvement while working in a collaborative, modern tech environment.

Responsibilities

  • Design, build, and maintain backend systems for large-scale SaaS applications
  • Lead architecture and technical design discussions
  • Write high-quality, maintainable code and perform detailed code reviews
  • Mentor and guide junior engineers
  • Collaborate cross-functionally with product, design, and business teams
  • Continuously improve performance, scalability, and system robustness

Tech Environment

  • Backend: Python
  • Frontend: React, TypeScript
  • Cloud: AWS, GCP
  • Database: MongoDB, MySQL, Redis
  • Container & CI/CD: Docker, GitHub Actions, Jenkins
  • Architecture: Domain-Driven Design (DDD)

Qualifications
Must-Have:

  • 3+ years of backend or full-stack development experience
  • Strong coding skills in Python or other backend languages
  • SaaS product development experience
  • Technical mentorship or team leadership experience
  • Cloud deployment experience (AWS/GCP)
  • Familiarity with relational and NoSQL databases

Nice-to-Have

  • Experience in large-scale SaaS architecture
  • Automated testing or CI/CD implementation
  • Knowledge of DDD or scalable design patterns

What's Offered

  • Hybrid work flexibility
  • Competitive salary and stock options
  • AI tool usage covered (e.g., ChatGPT, Claude)
  • Learning and development budget
  • Refresh and housing allowances

Selection Process
Resume → Coding Test → Interviews → Final Interview



  • Minato City Mercari, inc. ¥1,000,000 - ¥1,500,000 per year

    フリマアプリ「メルカリ」のグロースを支えるための基盤開発を行うエンジニアを募集しております。Growth Platformは、メルペイのみならずメルカリグループ(メルカリ、メルペイ、メルコイン、メルカリShopsなど)のグロースに用いるマーケティングツールや、クーポン、ポイント還元システムなどの開発・運用を行うチームです。 ...


  • Tokyo TIER IV

    自動運転で発生するデータの収集・検索・分析を支えるデータ基盤の開発・運用を担当していただきます。 · 車両からの走行データを収集・加工するデータパイプラインの開発・運用 · 走行履歴や統計情報を提供するAPIの開発・運用 · ...


  • Tokyo TIER IV ¥5,316,000 - ¥59,496,000 per year

    自動運転の開発に重要な機械学習基盤の開発を担当していただきます。ティアフォーでは、自動運転の安全性を高め、可用性を向上させる機械学習基盤を構築しています。 · 大規模なデータを取り扱い、継続的なモデルの改善を実現する機械学習基盤が求められています。 · ...


  • Tokyo TIER IV

    Tierra Fora desarrolla un sistema llamado Web.Auto para apoyar la implementación y operación de sistemas de conducción automática. · Desarrollar el diseño, desarrollo y pruebas del servicio Backend de WebAuto. · Liderar al equipo técnico para decidir las políticas técnicas. · Dis ...


  • Shinjuku W3Global ¥8,000,000 - ¥15,000,000 per year

    As a Senior Backend Engineer, you will play a key technical leadership role in developing and scaling a fast-growing SFA/CRM SaaS product. · Design, build, and maintain backend systems for large-scale SaaS applications · Lead architecture and technical design discussions · Write ...


  • Minato Mercari, Inc. ¥20,000,000 - ¥25,000,000 per year

    フリマアプリ「メルカリ」のグロースを支えるための基盤開発を行うエンジニアを募集しています。Growth Platformは、メルペイのみならずメルカリグループ(メルカリ、メルペイ、メルコイン、メルカリShopsなど)のグロースに用いるマーケティングツールや、クーポン、ポイント還元システムなどの開発・運用を行うチームです。 ...


  • Shinjuku-ku, Tokyo W3Global ¥960,000 - ¥1,800,000 per year

    As a Senior Backend Engineer, you will play a key technical leadership role in developing and scaling a fast-growing SFA/CRM SaaS product. This position focuses on backend architecture, team mentorship, and code quality improvement while working in a collaborative, modern tech en ...


  • Tokyo TIER IV ¥483,000 - ¥1,166,000

    自動運転で発生するデータの収集・検索・分析を支えるデータ基盤の開発・運用を担当していただきます。 · ...


  • Tokyo TIER IV ¥483,000 - ¥1,666,000

    自動運転の開発に重要な機械学習基盤の開発を担当していただきます。 · ティアフォーでは、自動運転の安全性を高め、可用性を向上させる機械学習基盤を構築しています。 · ...


  • Tokyo 株式会社ジーニー ¥1,000,000 - ¥1,500,000 per year

    急成長中のSFA/CRMプロダクトを技術的にリードするバックエンドエンジニアとして、設計・開発からチームの成長支援まで幅広くお任せします。 · ソフトウェア開発・技術課題の解決 · 高品質かつ高性能なソフトウェアアプリケーションやシステムの設計・開発・保守 · 複雑な技術的課題(パフォーマンス改善、技術負債解消など)に対する創造的かつ効果的な解決策の検討〜実行 · チームリード・育成・開発プロセス推進 · ジュニアエンジニアへの指導・メンタリングを通じての、技術的知見共有 · チームメンバーの開発進捗の把握、課題の特定、解決のサポート · コードレビュー ...


  • Shinjuku-ku, Tokyo W3Global ¥8,000,000 - ¥15,000,000 per year

    We are seeking a Senior Frontend Engineer to take ownership of our next-generation SaaS sales and CRM platform. You'll lead frontend architecture, enhance performance and UI design, and mentor a growing team of talented developers. · Architect and implement scalable frontend solu ...


  • Shinjuku W3Global ¥8,000,000 - ¥15,000,000 per year

    We are seeking a Senior Frontend Engineer to take ownership of our next-generation SaaS sales and CRM platform. You'll lead frontend architecture, enhance performance and UI design, and mentor a growing team of talented developers. · Architect and implement scalable frontend solu ...


  • 東京都 千代田区 丸の内, 株式会社はーとふるセゾン

    This position creates an environment where MiiTel developers can work more efficiently based on Platform Engineering practices. You will be responsible for providing internal products to other teams, improving infrastructure operations, managing OpenSearch and promoting SRE. · ...


  • Tokyo Cybereason ¥800,000 - ¥1,200,000 per year

    We're seeking an experienced Fullstack Backend Engineer to join our team working on Cybereason's platform. · Design and develop scalable backend services and intuitive front-end interfaces for our platform · Implement data ingestion and processing pipelines for large volumes of s ...


  • Tokyo 株式会社ジーニー

    We're hiring a Senior Backend Engineer to lead our enterprise rollout through technology. · About Geniee Inc. · We were founded in April 2010 with the goal of creating a global tech company from Japan like GAFA. We went public only seven years after our founding and have kept inc ...


  • Tokyo, Tokyo G Talent ¥7,000,000 - ¥16,000,000 per year

    +Backend Engineer (AI Product and Infrastructure Team) | Portal Site, App DevelopmentBusiness Level Japanese Required (N2 Level) · +Fully Remote Work+Listed Company+In-house Products/Services+Great Welfare ...


  • tokyo Talisman Corporation

    Job Opportunity with a FinTech Company in Japan. · Design develop and maintain high-performance backend systems with Kotlin or Java · Engage in collaborative efforts with cross-functional teams to conceptualize architect implement new features that enhance our SaaS offerings. · ...


  • Shinjuku W3Global ¥15,000,000 - ¥20,000,000 per year

    A fast-growing AI startup is seeking a Senior Backend Engineer to join their AI Agent Framework team. This role is ideal for experienced backend developers passionate about cutting-edge technologies in Large Language Models (LLMs), natural language processing, and multi-agent sys ...


  • Tokyo Rakuten India ¥94,000 - ¥140,000 per year

    We are looking for backend engineers that are interested building and running a data platform for data processing applications. This is a full-time, on-site role located in Tokyo, Japan. The Senior Backend Engineer will be primarily responsible for designing, developing, and main ...


  • Tokyo Specialized Group Remote job

    A fast-scaling digital service company is seeking a Senior Backend Engineer to help design and build the next generation of its data-driven platform. · ...


  • Tokyo, Japan AheadGroup $120,000 per year

    Ahead Group is seeking a Senior Backend Development Engineer focused on point-related products for one of our Global E-Commerce clients. · Lead backend development initiatives for point related products. · Collaborate with Product Managers, Project Managers, and business stakehol ...