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Visually construct structured LLM prompts with role blocks, variable injection, and multi-format export.
The AI Prompt Builder is a visual, block-based editor for constructing structured LLM prompts. It supports System, User, and Assistant message roles, template presets for common personas like Code Reviewer or SQL Expert, and dynamic variable injection using {{variable}} syntax. The built-in token estimator gives real-time feedback on prompt length.
Select a role template from the dropdown or start with a blank prompt. Add message blocks by clicking the System, User, or Assistant buttons, then type your content. Use {{variable}} placeholders to mark dynamic fields. Switch between export formats — JSON messages array, Plain Text, or XML for Claude — and copy the result instantly.
Crafting well-structured prompts is the single biggest factor in LLM output quality. This tool eliminates manual formatting, prevents role-ordering mistakes, and lets you iterate on prompt structure visually without switching between your editor and the AI playground.