Build reusable prompt templates with {{variable}} placeholders — enter variable names (one per line or comma-separated) and get a ready-to-fill template with a variable reference list. Updates live as you type.
Enter one variable per line or separate with commas. Names are converted to snake_case automatically.
Frequently Asked Questions
What does the Prompt Variable Builder do?
It creates a prompt template with {{variable}} placeholders from a list of variable names, plus a reference section listing each variable and its purpose.
What syntax do the placeholders use?
Variables use double curly braces: {{variable_name}}. This format works with many prompt tools, automation scripts, and AI workflow platforms.
How are variable names formatted?
Names are converted to lowercase snake_case — “Word Count” becomes {{word_count}}. Special characters and spaces are removed or replaced with underscores.
Can I format the template after building?
Yes. Copy the output into the Prompt Formatter to clean up markdown headings and spacing.
Is this tool free and does it work on mobile?
Yes on both counts. The Prompt Variable Builder on draft21 is completely free with no sign-up required and works on all devices.