features
x47 is packed with features designed for prompt engineers, AI developers, and researchers who need to test and compare LLM outputs efficiently.
Multi-Model Testing
Run the same prompt across multiple LLMs simultaneously. Compare how GPT, Claude, Gemini, DeepSeek, and Llama respond to identical inputs.
- •Test prompts against 5+ providers at once
- •Identify which model performs best for specific tasks
- •Understand different model behaviors and strengths
- •Save time compared to testing models individually
Side-by-Side Comparison
View outputs from multiple models in a split view for easy comparison. Quickly identify differences in tone, accuracy, and completeness.
- •Toggle between tabs and split view modes
- •Compare 2-4 outputs at once
- •One-click copy to clipboard
- •Markdown rendering for formatted outputs
Variable Injection
Create reusable prompt templates with dynamic variables. Use $variable_name syntax to define placeholders that are replaced at runtime.
- •Build templates once, reuse with different inputs
- •Auto-detection of variables in prompts
- •Real-time preview of compiled prompts
- •Perfect for A/B testing prompt variations
Prompt Chaining
Chain multiple prompts together for complex multi-step workflows. Each step can build on the context from previous steps.
- •AI-assisted chain generation
- •Sequential execution with context passing
- •Edit and reorder steps easily
- •Export chains as JSON for reuse
Output Evaluation
Automatically evaluate model outputs using AI. Get scores for task success, instruction following, factuality, safety, and clarity.
- •5 evaluation metrics per output
- •Visual score bars for quick comparison
- •Detailed feedback and comments
- •Powered by GPT-5.1 for consistent evaluation
History & Persistence
All your prompts and outputs are automatically saved. Browse history, search past runs, and export data for analysis.
- •Automatic saving of all runs
- •Search by keyword, model, or content
- •Up to 1000 history entries
- •Export as JSON for backup
Local-First Privacy
Your data stays in your browser. API keys and history are stored in localStorage, never sent to x47 servers.
- •API keys stored locally only
- •No data collection or tracking
- •Works offline after initial load
- •Full control over your data
Keyboard-First Design
Optimized for power users with comprehensive keyboard shortcuts. Execute prompts, navigate tabs, and manage outputs without touching the mouse.
- •Ctrl+Enter to run prompts
- •Tab navigation shortcuts
- •Quick access to all features
- •Customizable keybindings
workspace_features
Multi-Tab Workspace
Create unlimited tabs for different prompts or projects. Each tab maintains its own system prompt, user prompt, selected models, settings, and variable values. Switch between tabs instantly without losing context.
Persistent State
Your workspace is automatically saved to browser storage. Close the browser and come back later - your tabs, prompts, and settings will be exactly as you left them.
Real-Time Preview
See your compiled prompt with variables replaced before executing. This helps catch errors and ensures your dynamic content is formatted correctly.
model_configuration
Fine-tune how models respond with these adjustable parameters:
Creativity
Controls randomness (temperature). Lower values = more focused, higher = more creative.
Response Length
Set output length from short (256 tokens) to very long (4000 tokens).
Output Format
Request free text, bullet points, tables, or JSON structured output.
Repetition Penalty
Reduce repetitive phrasing by penalizing recently used tokens.