AI Tools Tool updated 1 month ago

Prompt Variable Replacer

Fill {{variables}} in prompt templates with a live preview. Paste a template, fill the detected variables, and copy the final prompt instantly. Everything runs in your browser — nothing is sent to a server.

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Use Prompt Variable Replacer

Prompt Variable Replacer

Fill the placeholders in any prompt template and copy the finished prompt. Everything runs in your browser — nothing is sent to a server.

1 · Choose a template
Empty template
2 · Fill the blanks
0 / 0 filled

Click a chip to fill it. Enter saves, Esc cancels.

3 · Your prompt
Incomplete
Filled placeholders are highlighted green, empty ones amber. Empty values keep the variable visible in the output.
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Read Content

Learn how the tool works and when to use it.

How to Use This Tool

Paste any prompt template that uses {{variable}} placeholders, or click Load sample to try a ready-made example. The tool detects every placeholder and builds a list of fields below.

1. Paste your template

Write or paste a prompt with placeholders such as {{role}}, {{topic}} or {{length}}. Placeholders must contain only letters, digits and underscores, and must start with a letter or underscore.

2. Fill the variables

Each detected variable gets its own input field. Type a value for each one, or click Fill all with sample to add realistic values instantly. Use Bulk paste to paste many values at once in a name=value format, one per line.

3. Copy the final prompt

The final prompt updates live as you type. Filled placeholders are highlighted in green; empty ones stay visible in amber. Copy the result, copy the raw template, or save the output as a .txt file.

Features

  • Live token and character counter for the final prompt
  • Malformed placeholder warnings (empty, invalid names, unclosed braces)
  • Per-variable usage count when a placeholder appears more than once
  • Auto-save: your template and values are saved in the browser
  • Presets: save and reload template versions
  • Undo after clearing values

FAQ

Short answers for the questions users ask before trusting the result.

A prompt variable is a placeholder such as {{topic}} inside a template. It lets you reuse the same template for many prompts by swapping in different values, which is especially useful for LLM workflows.

No. Everything runs in your browser. Your template and values are stored only in your browser's local storage and are never transmitted to any server.

Double curly braces with a name, like {{role}} or {{num_examples}}. Names can contain letters, digits and underscores, and must start with a letter or underscore.

Yes. Your current template and values are auto-saved in the browser, and you can also save named presets to switch between different templates.

Empty placeholders stay visible in the output and are highlighted in amber so you can see exactly what is still missing before you copy the final prompt.

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