PromptForge
Prompt Engineering Playground
Build, test & optimize AI prompts with real-time scoring, variable injection, 12+ templates, and best-practice analysis. Free, private — runs entirely in your browser.
Why PromptForge?
Multi-Turn Builder
Build system, user, and assistant messages with drag-and-drop reordering. Craft complex multi-turn conversations with ease.
Variable Injection
Use {{variable}} syntax to create reusable prompt templates. Fill variables in the sidebar and see changes live.
Real-Time Scoring
Get instant feedback on prompt quality: clarity, specificity, format definition, constraints, and chain-of-thought usage.
12+ Templates
Pre-built templates for Code Review, Blog Writing, SQL, Data Analysis, API Design, Testing, and more. One-click load.
Best Practice Tips
Automated analysis detects common anti-patterns and suggests improvements based on proven prompt engineering techniques.
Export Anywhere
Copy as Messages JSON, Claude API format, or plain text. Ready for any LLM — Claude, GPT, Gemini, or your own.
Token Estimation
See estimated token counts per message and total. Plan your API costs before making a single request.
100% Private
All processing happens in your browser. Your prompts, variables, and data never leave your machine. Zero server requests.
Frequently Asked Questions
What is prompt engineering?
Prompt engineering is the practice of designing and optimizing inputs (prompts) to AI language models to get better, more accurate outputs. It involves techniques like role definition, chain-of-thought reasoning, few-shot examples, and output formatting. PromptForge helps you apply these techniques interactively.
Which AI models does this work with?
PromptForge generates standard message formats that work with any LLM API — Claude (Anthropic), GPT (OpenAI), Gemini (Google), Llama, Mistral, and more. The Claude API export format is specifically optimized for Anthropic's API.
How does the prompt scoring work?
The scoring system analyzes your prompt for best practices: role definition, output format specification, examples, constraints, chain-of-thought instructions, and overall specificity. Each factor adds or subtracts from your score, giving you actionable feedback to improve.
What are prompt variables?
Variables (written as {{variable_name}}) are placeholders in your prompt that can be filled with different values. This makes your prompts reusable — create one template and use it for many situations by just changing the variables.
Is this connected to an AI API?
No. PromptForge is a prompt builder and optimizer — it helps you craft prompts locally in your browser. It does NOT send prompts to any AI model. Once you've built your prompt, export it and use it with your preferred AI provider.