Join one of Japan's leading internet services companies as a PHP Full Stack Engineer, working on authentication infrastructure that supports a large-scale digital ecosystem used by millions of users.

In this role, you will design and implement Single Sign-On (SSO) authentication solutions using PHP, Yii, OIDC, and OAuth 2.0. You will work across both frontend and backend development, building secure login experiences and scalable authentication services integrated with Oracle Database.

This is an opportunity to deepen your expertise in PHP development, web security, authentication platforms, and large-scale systems while collaborating with global engineering teams in Tokyo.
Key Responsibilities

• Design and implement secure OIDC (OpenID Connect) and OAuth 2.0 authentication flows using PHP and the Yii framework.
• Develop intuitive, user-facing login interfaces that provide seamless and secure Single Sign-On (SSO) access for merchants and partners.
• Build scalable backend services for token issuance, validation, and management, integrating authentication functionality with Oracle Database.
• Apply robust web security standards and engineering practices to protect authentication systems against data breaches and unauthorised access.
• Collaborate with cross-functional and global engineering teams to integrate SSO solutions into existing merchant portals and digital services.

Required Skills and Qualifications Experience:

• 3+ years of web application development experience using PHP and the Yii framework.
• Hands-on development experience and strong technical understanding of OIDC (OpenID Connect) and OAuth 2.0 protocols.
• Strong experience with Oracle Database, including SQL development, stored procedures, and performance tuning.
• Ability to work across frontend and backend development within web-based applications and authentication systems.

Soft Skills:

• Strong cross-functional communication skills with the ability to explain technical solutions clearly across diverse teams.
• Proactive problem-solving approach with a focus on security, system performance, and user experience.
• Ability to collaborate effectively with international and multidisciplinary engineering teams.
• Detail-oriented approach to developing reliable and secure authentication functionality.

Language Requirements:

• Japanese: Business level or above for written and verbal communication.
• English: Basic level.

Preferred Skills & Qualifications

• Experience developing or integrating Single Sign-On (SSO) platforms within high-traffic or large-scale web systems.
• Practical knowledge of web security technologies and standards, including JWT, data encryption, and secure cookie handling.
• Experience working within Agile or Scrum development environments.
• Familiarity with API development and documentation tools such as Swagger or OpenAPI.
• Experience developing secure authentication or identity management solutions for e-commerce, fintech, or other large-scale digital platforms.

About the Company
Our client is one of Japan's leading internet services and technology companies, operating a large global digital ecosystem serving hundreds of millions of users.

As part of the company's core membership and authentication platform environment, engineers contribute to high-impact infrastructure supporting e-commerce, digital services, user authentication, and secure online transactions.

The organisation offers an international engineering environment where developers can work with modern technologies and contribute to resilient, scalable systems used across major digital services.
Why You'll Love Working Here

• Work on large-scale SSO and authentication infrastructure supporting a major Japanese internet services ecosystem.
• Build valuable technical expertise across PHP, Yii, OIDC, OAuth 2.0, Oracle Database, and web security.
• Enjoy a hybrid working model with four days in the office and one day working from home.
• Access an on-site employee food hall with daily meals provided for added convenience.
• Work in a modern, casual dress environment alongside international and cross-functional technology teams.

Don't Miss Out - Apply Now!