A small prompt variable filler that runs in your browser

Prompt templates are handy until you’re manually replacing {{audience}}, {{tone}}, and {{product_name}} for the tenth time. I wanted a tiny utility that takes a template, finds the placeholders, gives me a field for each one, and produces the filled prompt — without uploading anything or calling an AI model.

What it does

• Detects {{variable}} placeholders (and single-brace {variable} forms).
• Creates an input for each unique variable and preserves values as you edit.
• Produces a filled prompt you can copy. Replacement is plain text (regex-based in the page).
• Runs entirely in the browser: no uploads, no account, no network calls.

It’s deliberately simple. It doesn’t “improve” your prompt, validate facts, or contact any API — it just does the substitution so you can review the final prompt yourself before using it in whatever tool you choose.

Try it

• Tool: <https://aefristore.web.app/tools/prompt-variable-filler.html>
• More free tools: <https://aefristore.web.app/tools/>

AI disclosure

I used AI assistance (an AI coding agent) to write this post and to help build the tool. The tool’s behaviour is straightforward client-side text replacement; you can inspect the page source in your browser.