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AI Prompt Architect
All tools free — no signup required

Prompt Engineering Tools

Score, generate, optimise, and test AI prompts using the STCO framework. Built for developers and prompt engineers who want consistent, high-quality AI outputs.

10
Free Tools
50+
Tech Stacks
73%
Fewer Hallucinations
0
Signup Required

Our Prompt Engineering Toolkit

Every tool is built on the STCO framework — the methodology proven to reduce AI hallucinations by 73%.

AI Prompt Scorer

Most Popular

Score any prompt 0–100 in seconds

Paste any prompt and get a detailed quality score based on the STCO framework. Evaluates System role, Task clarity, Context completeness, and Output constraints — with AI-powered improvement suggestions.

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AI Prompt Generator

Core Tool

Build production-grade prompts visually

Step-by-step visual wizard that generates Master Prompts for 50+ tech stacks. Encodes architecture, coding standards, and security rules into structured prompts that prevent context collapse.

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System Prompt Builder

Design bulletproof system prompts

Build system prompts with persona definitions, behavioural rules, guardrails, and output schemas. Exports ready-to-use system instructions for ChatGPT, Claude, Gemini, and Cursor.

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Prompt Checker

Find gaps before you hit send

Analyses your prompt structure and identifies missing STCO dimensions, ambiguous instructions, and hallucination risks. Get actionable fix suggestions instantly.

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Prompt Optimizer

Rewrite prompts for maximum clarity

AI-powered prompt refinement that restructures freestyle prompts into STCO format. Reduces token waste by up to 41% while improving output quality.

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Prompt Playground

Test prompts across models side-by-side

Run the same prompt against GPT-4o, Claude 4, and Gemini 2.0 simultaneously. Compare response quality, latency, and cost per output in real time.

3 Free / Unlimited on ProTry it

Token & Cost Calculator

Calculate costs across 10+ models

Paste any text to see exact token counts and cost estimates for GPT-4o, Claude 4, Gemini 2.0, Llama 3, Mistral, and more. Includes per-model price comparison tables.

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ROI Calculator

Prove the business case for structured prompting

Input your team size and AI usage patterns to generate ROI projections. Shows time savings, cost reductions, and productivity gains — exportable as a shareable report.

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Prompt Security Scanner

Detect injection vulnerabilities

Scans prompts for prompt injection risks, jailbreak patterns, and data leakage vectors. Generates a security report with remediation steps.

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JSON-LD Schema Validator

Validate structured data for AEO

Paste JSON-LD and validate against schema.org specifications. Checks Article, FAQPage, HowTo, BreadcrumbList, and SpeakableSpecification schemas for AEO compliance.

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Cursor Rules Generator

New

Generate .cursorrules for any stack

Build production-ready .cursorrules files for Cursor AI IDE. Select your language, framework, coding standards, and conventions — get a downloadable rules file instantly.

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How Structured Prompting Works

1

System

Define the AI's role, expertise, and behavioural rules

2

Task

State exactly what you want — specific, measurable, actionable

3

Context

Provide project details, audience, constraints, and examples

4

Output

Specify format, length, tone, and quality constraints

Frequently Asked Questions

What are the best free prompt engineering tools?
The best free prompt engineering tools are AI Prompt Architect's suite: Prompt Scorer (quality scoring 0–100), AI Prompt Generator (visual STCO builder for 50+ tech stacks), Token Calculator (cost estimates across 10+ models), System Prompt Builder (persona + guardrails), and Prompt Security Scanner (injection detection). All are free with no signup required.
How do I score the quality of my AI prompt?
Use the AI Prompt Scorer at aipromptarchitect.co.uk/prompt-scorer. Paste your prompt and receive a score from 0 to 100 based on four STCO dimensions: System role clarity, Task specificity, Context completeness, and Output format constraints. The tool provides specific improvement suggestions for each dimension.
Can I use these prompt engineering tools for free?
Yes. 9 out of 10 tools are completely free with no signup required: Prompt Scorer, AI Prompt Generator, System Prompt Builder, Prompt Checker, Prompt Optimizer, Token Calculator, ROI Calculator, Security Scanner, and Schema Validator. The Prompt Playground (multi-model comparison) has 3 free uses per month, with unlimited access on the Pro plan.
What is the STCO framework used by these tools?
STCO stands for System, Task, Context, Output — a structured prompt engineering framework that reduces AI hallucinations by 73%. System defines the AI's role and constraints. Task states the specific action. Context provides background data. Output specifies the response format. All AI Prompt Architect tools use STCO as their underlying evaluation and generation framework.

Up to 50% API cost reduction—LLM Economics Review