Free Online Robots.txt Generator and Validator

This application is a professional-grade SEO utility designed to help website owners, developers, and SEO specialists generate and audit their robots.txt files directly in their browser. It provides a visual interface to build complex crawling rules without needing to manually write the syntax.

Core Features

• Visual Rule Builder: A user-friendly form to add directives (User-agent, Disallow, Allow, Crawl-delay, Sitemap) without writing raw text.
• Real-time Live Preview: An editable text area that updates dynamically as you modify the rules in the builder.
• Syntax Validator: An integrated engine that runs client-side checks to highlight syntax errors, missing trailing slashes, or logical conflicts.
• One-Click Copy: Fast clipboard integration to copy the finalized robots.txt content.
• Import Mode: Paste an existing robots.txt file into the editor to automatically parse and load the rules into the visual builder for easy editing.

UI Layout & Design

• Header: Contains a clear, descriptive H1 title and a brief instructional subtitle.
• Two-Column Layout:
  • Left Column (The Builder): A structured form area with input fields for User-agents and directory paths. Includes buttons to add/remove rule groups.
  • Right Column (The Preview): A read-only (but copyable) code block showing the generated robots.txt output, styled with monospaced typography.
• Validation Panel: Located beneath the columns, a dynamic area that displays success messages (green) or error logs (red/amber) if the syntax is broken.

Color Palette (Light-Mode Only)

• Primary Background: #FFFFFF
• Surface Background: #F8FAFC
• Primary Text: #1E293B
• Accent Color: #2563EB (for buttons and active states)
• Border Color: #E2E8F0
• Success Color: #16A34A
• Error Color: #DC2626

Technical Implementation Directives

• Single-File Constraint: All HTML, CSS, and JavaScript must exist within a single file. Do not use external CSS or JS frameworks that require bundling (Bootstrap/Tailwind via CDN is acceptable).
• Sandbox Compatibility:
  • Storage: Do not use localStorage, sessionStorage, or cookies. Maintain all data state strictly in volatile JavaScript variables.
  • Popups: Do not use alert(), prompt(), or confirm(). All user feedback must be rendered as custom modal overlays or inline DOM elements.
• Responsiveness: Use CSS Flexbox/Grid to stack the columns vertically on screens smaller than 768px.
• Animations: Use CSS transition (e.g., transition: all 0.2s ease-in-out) for all interactive elements, including button hover states and validation message appearances.