# Prompt variable templater

> Fill named variables without executing template code.

[Open tool](https://www.toolcabana.com/yi/prompt-template) · [AI and prompt tools](https://www.toolcabana.com/yi/category/ai-and-prompt-tools)

Tool ID: prompt-template. Requested language: yi. Description language: en. Complete guide translation: no; untranslated sections use English.

## Overview (en)

Prompt variable templater fills {{placeholders}} in a prompt with values from a JSON object you provide, using plain text substitution with no template code executed. Placeholder names start with a letter or underscore and may contain dots or hyphens, spaces inside the braces are allowed, and any placeholder without a matching key stops the run with a list of the missing names.

## Supported tasks (en)

Fill named variables without executing template code.

## Steps (en)

1. Paste the source into the input editor, or load the built-in example.
2. Set variables (json object).
3. Run prompt variable templater, review the output, then use the available copy or download controls.

## Settings

- Variables (JSON object) (en; key: variables; type: textarea)

## Limitations (en)

Text operations generally accept up to 2,000,000 characters. Individual parsers, generators and formulas apply additional limits shown by their controls.

## Example input

```text
Explain {{topic}} to {{audience}} with one example.
```

## Privacy and connections (en)

This operation processes its source in your browser. Copy and download are explicit actions; source input is not saved in an account or history.

## Questions (en)

### How do I format variables for the prompt templater?

Enter a single JSON object whose keys match your placeholder names, for example topic and audience keys for {{topic}} and {{audience}}. Arrays, plain strings and invalid JSON are rejected with the message that variables must be a JSON object.

### What happens if a variable is missing from the JSON?

The tool lists every placeholder that has no matching key, for example Missing variables: audience, and produces no output until you add them. Extra keys that do not appear in the template are ignored.

### Can I use nested objects or dotted names like {{user.name}}?

Dotted names are allowed but matched literally, so {{user.name}} needs a top-level key named user.name; nested lookup is not performed. If a value is itself an object or array, it is inserted as compact JSON text.

### Where is my input processed?

This operation processes its source in your browser. Copy and download are explicit actions; source input is not saved in an account or history.

### What are the input limits?

Text operations generally accept up to 2,000,000 characters. Individual parsers, generators and formulas apply additional limits shown by their controls.

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