Mustache-style variables
Wrap variable names in double curly braces: {{role}}, {{code-snippet}}. The tool detects all variables automatically and creates an input field for each one.
Prompt Template & Variable Injector
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Build and manage prompt templates with mustache-style variables. Auto-detects variables, renders input fields, and compiles prompts in real-time. Save templates to localStorage. All processing is local.
Your data stays in your browser.
Templates and variables are stored only in localStorage on your device. Nothing is uploaded.
Use {{variable-name}} syntax for variables. Fields are generated automatically as you type.
0 variables detected
Variables
Edit the template above to add or remove {{variables}}. Variable names can contain letters, numbers, hyphens, and underscores.
Compiled Prompt
Fill in the variable fields above to see the compiled prompt in real time.
How it works
Real-time compilation
As you type in the template or variable fields, the compiled preview updates instantly. Undefined variables appear as-is in the output.
Local persistence
Templates are saved to your browser's localStorage. They persist across page reloads but are specific to your device and browser.
Frequently Asked Questions
- No. All template processing and variable substitution happens entirely in your browser. Your prompts never leave your device.
- Templates are saved in your browser's localStorage. They are specific to this device and browser and will persist across page reloads.
- Yes. Once the page is loaded, everything runs locally. No internet connection is required.
The Importance of Reusable Prompt Templates
Consistency across tasks
Templates standardize how you ask the model to perform recurring tasks—code review, summarization, data extraction—so results are predictable and repeatable across sessions and team members.
Faster iteration
Save a template once and reuse it with different inputs. Change the variable values, not the instructions, to test variations quickly without rewriting the whole prompt.
Version control friendly
Template text is plain text. Store it in files, track changes with git, and share prompts across your team the same way you share code.
Dynamic Variable Injection in LLM Workflows
Mustache-style syntax
Wrap placeholder names in double curly braces—{{role}}, {{language}}, {{goal}}—and the tool generates an input field for each one automatically.
Real-time preview
As you fill in variables, the compiled prompt updates instantly. You see exactly what the model will receive before you copy it.
Local persistence
Templates are saved to your browser's localStorage, so they survive page reloads and remain specific to your device and browser.
Best Practices for System Prompts
Define the role clearly
Start with a strong role statement ("You are an expert Python code reviewer...") to set the model's behavior and tone before giving it any task-specific instructions.
Separate instructions from data
Use variables for user-supplied content (code snippets, text to analyze) so the model can't be tricked into following instructions hidden inside the input data.
Iterate and measure
Test your template with different inputs, check the compiled output, and refine the wording. Small wording changes can significantly improve model accuracy.