Business Application Created in 30 Minutes Using Claude Code
November 5, 2026 · 2 min read
A business application was developed within 30 minutes using Claude Code, an AI agent designed for programming. The process utilized a method called vibe coding, where the user provides goals and conditions in Japanese for the AI to implement, followed by verification and correction, rather than writing code line by line.
The application functions as a reminder tool. It reads two Excel files containing customer lists and submission statuses to identify who needs to be reminded of what. After human approval, the tool generates a list of non-submissions and drafts reminder emails. While the tool can be scheduled for automatic execution via Task Scheduler to create the initial list, the final act of sending emails remains a human task.
Development began by creating a CLAUDE.md file in a designated workspace. This file serves as a set of rules that Claude Code references in every session to maintain consistency regarding requirements and prohibitions, such as not sending emails automatically or not modifying original files. The AI agent then developed a Python program, which included a two-stage process of verification followed by output.
To ensure accuracy, the tool was tested with sample data. Claude Code identified that if the current date were used as a baseline, no deadlines would be expired, leading the agent to implement a feature allowing the user to specify a reference date. The final output was verified against the original data to ensure no records were missed or altered.
Regarding future expansions, the Model Context Protocol allows Claude to interact directly with Google Sheets or chat tools. However, for business applications, using APIs is recommended for better stability. The author emphasizes that when handling personal information, such as names and email addresses, users should consult with information systems or legal departments and share the CLAUDE.md file to expedite the discussion.