About the Developer
Background and expertise of ykarmr, developer and operator of USEFUL TOOLS
Operated by a Trusted Developer
Developed and operated by a web engineer with 5 years of professional experience, utilizing extensive large-scale development experience from corporate environments. Maintains transparency through open-source approach and continuous service improvement.
Greetings
Hello! Thank you for using USEFUL TOOLS. This site is developed and operated by ykarmr with love, based on the concept of 'simple tools for daily use'. I hope it makes your daily life even a little more convenient.
USEFUL TOOLS Vision
Vision
We aim for 'a world where everyone can instantly access the tools they need, when they need them.' No complex operations or registration required. We strive to provide tools that are ready to use the moment you open them.
Mission
To continuously create tools that solve everyday 'minor inconveniences.' We listen to user feedback and provide truly needed features with simple and beautiful design.
Development Values
Pursuit of Simplicity
We believe 'usability' is not about the number of features, but about how easily you can reach the features you need. We focus on UI design that allows users to achieve their goals quickly and without confusion.
User First
We prioritize user experience over technical constraints. We actively incorporate feedback and continue improvements from the perspective of actual users.
Commitment to Quality
We don't just aim for 'it works' but for 'it feels good to use.' We develop with consideration for performance, accessibility, and security.
Developer Profile
ykarmr
Frontend Engineer & Independent Developer
Professional Experience & Expertise
Medium-scale Electronic Medical Record System Development
Responsible for frontend development of electronic medical record systems for medical institutions. Interface design and implementation with emphasis on usability and security.
Mobile Carrier Integrated Media Site Renewal
Participated in a large-scale frontend renewal project for a mobile carrier's integrated media site. Responsible for requirement review from scratch, frontend design and implementation focused on user experience improvement, and infrastructure setup.
Technical Expertise
Core Technologies
- • TypeScript: 5 years of professional experience
- • React: 5 years of professional experience
- • Next.js (Pages Router): 3 years
- • Next.js (App Router): 2 years
Related Technologies
- • Tailwind CSS, CSS-in-JS
- • Node.js, Fastify
- • Git, GitHub Actions
- • Docker
- • Test design & implementation
Continuous Learning & Growth
Constantly keeping up with the latest technology trends, actively utilizing AI technologies like GitHub Copilot, ChatGPT, and Claude to improve development efficiency. Practicing a new development style that combines human creativity with AI capabilities.
Reliability & Transparency
Open Source
Code is publicly available, maintaining transparency. Quality can be verified by anyone.
Continuous Operation
Long-term perspective for continuous service improvement and operation.
Quality Assurance & Security
Quality Management
Leveraging extensive large-scale development experience from corporate environments, implementing development practices that emphasize performance and accessibility.
Security Measures
Browser-only design that doesn't handle personal information.
Service Features & Achievements
Emphasis on Practicality
Providing 'truly useful' tools born from professional experience. Carefully selected practical features aimed at daily work efficiency.
User First
Feature design that prioritizes user needs. Pursuing intuitive UI/UX with emphasis on usability.
Technical Reliability
Type safety through TypeScript, performance optimization through Next.js. Sustainable development with modern technology stack.
Privacy Protection
Browser-only design that doesn't handle personal information. Data is processed locally and not transmitted externally.
Technical Specifications & Implementation
Adopted Technologies
Frontend
- • Next.js 15 (App Router)
- • React 18 (TypeScript)
- • Tailwind CSS
Development & Operations
- • GitHub (Version Control)
- • Netlify (Hosting)
- • ESLint, Prettier (Quality Management)
Design Policy
Performance
- • Page acceleration through static generation
- • Image optimization & lazy loading
- • Bundle size optimization
Accessibility
- • Assistive technology support through ARIA attributes
- • Keyboard navigation
- • Color contrast consideration
Continuous Improvement & Future Outlook
Current Efforts
- Continuous collection and analysis of user feedback
- Regular performance and accessibility audits
- Continuous strengthening of security measures
- Research and consideration of new technology trends
Future Plans
- Development of advanced tools leveraging professional experience
- Expansion of AI-powered features
- Expansion of multilingual support and internationalization
- Improved transparency in development processes
We'd Love to Hear Your Feedback
An experienced engineer will directly receive your feedback and use it to improve the service. Please feel free to share any suggestions for new features, bug reports, or improvements to usability.