Backend Engineer

About this role

The backend engineer will help build Builder Work, a recruitment and job-change service focused on the construction industry. The initial business is a recruitment placement service, with planned expansion into direct sourcing and qualification support. The role works under the engineering lead and contributes from the early stage of the service.

Core work includes designing and developing a multi-dimensional matching engine, including matching logic and scoring. The engineer will also design job and job-seeker database schemas, develop APIs and the data platform, connect ANDPAD field data such as process and quality data, and develop statistical and analytical systems for large-volume data. Additional responsibilities include backend implementation for AI features, such as automatic résumé generation and career rating using LLMs, as well as internal systems for career advisors and corporate sales staff.

The engineer will participate in code reviews, clarify specifications with the planning and business sides, and help decide implementation approaches. The team uses AI coding agents such as Claude Code in daily implementation, code review, research, and testing. PR reviews, dependency update checks, security checks, and end-to-end testing are being standardized with AI agents.

Applicants should support the mission of Builder Work and ANDPAD and have approximately three years of experience developing web services as a backend engineer. The posting emphasizes initiative and the ability to move work forward independently and collaboratively. Preferred experience includes development in an environment with regular releases, query tuning, table design, code review that considers broad impact and data volume, and specification work with planning or business teams that includes non-functional requirements. Experience with search, recommendation, or matching systems; integrating generative AI or LLMs into products; Python development; large-scale products; or team leadership is also welcomed.

This is a full-time position with a three-month probationary period, during which working conditions do not change. Annual compensation is listed in the structured data as JPY 6 million to JPY 10 million and is decided individually based on experience and ability. The package includes a fixed overtime allowance equivalent to 45 hours per month. Salary increases and bonuses are provided twice a year.

The workplace is the Builder Work business unit's dedicated office in Suidobashi, Chiyoda, Tokyo. The work style is primarily office-based, although remote work can be discussed. Working hours are 10:00–19:00 under a flextime system with core hours from 11:00 to 15:00. Benefits include social insurance, specified office services, activity and social-event subsidies, influenza vaccination coverage, a book-purchase subsidy, and an employee stock ownership plan with an incentive. Allowances include commuting costs up to JPY 30,000 per month, remote-work payments, business-trip allowances, a nearby-housing allowance, and marriage and childbirth gifts. Holidays include Saturdays, Sundays, public holidays, annual paid leave, special leave at joining, summer and year-end holidays, nursing or caregiving leave, condolence leave, and maternity and childcare leave.

The current interview process is conducted online and usually consists of two or three interviews, although it may change according to the selection status. A 30-minute human-resources meeting is held at one of the first two interview stages, and reference letters are requested from two former colleagues through back check.