PromptCraft Lab
Systematic prompt engineering, evaluation and benchmarking studio.
PromptCraft Lab is a developer utility designed to bring software engineering rigor to prompt development. Test prompt revisions across multiple models simultaneously, measure regression rates on edge test cases, and analyze token costs.
The Problem
Prompt Engineering is Treated as Magic, Not Engineering
Developers edit prompts in web chats, without regression testing or token optimization benchmarks.
- •A change that fixes one edge case silently breaks 5 other test cases.
- •Comparing output quality across Claude, GPT, and Gemini requires manual copy-pasting.
- •Token bloating adds thousands of dollars to monthly API bills unnecessarily.
The Solution
Automated Prompt Evaluation & Diffing Studio
A clean workbench where every prompt version is version-controlled, run against assertions, and benchmarked for token efficiency.
- Multi-model split view comparing responses in real time.
- Automated assertions (JSON schema validation, regex checks, length limits).
- Token compressor suggesting concise phrasing without losing semantic nuance.
Prompt CI/CD Loop
Continuous validation for production prompt templates.
Draft Prompt
Write system instructions with dynamic variables
Run Matrix
Execute against 20 edge-case test inputs across 3 LLMs
Assert & Grade
Checks format compliance, sentiment, and accuracy
Export Code
Generate ready-to-use TypeScript/Python client code
Engineered Features
Live Model Arena
WorkbenchCompare 4 models simultaneously with synchronized temperature and top_p controls.
Assertion Test Suite
TestingDefine pass/fail rules for JSON structure, banned words, and hallucination bounds.
Token Optimizer
OptimizationAlgorithms suggest removals that reduce input tokens by 25-40% without degradation.
Technology & Models Used
Key Results & Production Metrics
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