Prompt A/B Test Designer

2 variants3.1K samples$13.30
A~0 tokens
B~0 tokens
Diff Viewvs

Enter prompts to see differences

What This Tool Does

Prompt A/B Test Designer is built for deterministic developer and agent workflows.

Design rigorous prompt experiments with sample size calculation, cost estimation, and evaluation frameworks. The scientific method for prompt engineering.

Use How to Use for execution steps and FAQ for constraints, policies, and edge cases.

Last updated:

This tool is provided as-is for convenience. Output should be verified before use in any production or critical context.

Agent Invocation

Best Path For Builders

Browser workflow

Runs instantly in the browser with private local processing and copy/export-ready output.

Browser Workflow

This tool is optimized for instant in-browser execution with local data handling. Run it here and copy/export the output directly.

/prompt-ab-test-designer/

For automation planning, fetch the canonical contract at /api/tool/prompt-ab-test-designer.json.

How to Use Prompt A/B Test Designer

  1. 1

    Define prompt variants

    Add two or more prompt variants using the variant editor. Each variant has a name and the full prompt text. The diff view highlights differences between variants.

  2. 2

    Configure experiment parameters

    Set the significance level (default 0.95), minimum detectable effect (default 5%), and baseline success rate. These determine the required sample size.

  3. 3

    Review sample size and cost

    The calculator shows the required samples per variant, total samples, and estimated experiment cost based on your selected model and average tokens per evaluation.

  4. 4

    Export the experiment plan

    Click Export Plan to generate a complete experiment document with hypothesis, variants, sample size rationale, metrics, timeline, and budget in markdown format.

Frequently Asked Questions

What is Prompt A/B Test Designer?
Prompt A/B Test Designer helps you design rigorous prompt experiments using statistical methods. It calculates required sample sizes for significance, estimates experiment cost, and generates evaluation framework documents.
How is sample size calculated?
Using two-proportion z-test power analysis with configurable significance level, minimum detectable effect, and baseline success rate. Bonferroni correction is applied for experiments with more than two variants.
Is Prompt A/B Test Designer free?
Yes. Completely free with no account or sign-up required.
Does it send my prompts to a server?
No. All calculations and prompt comparison happen entirely in your browser.
Can I export the experiment plan?
Yes. Export as a markdown document with hypothesis, variants, sample size rationale, success metrics, expected duration, and budget — ready for team review or documentation.