Stop guessing. Start testing prompts.
Compare prompt versions side-by-side. Test across GPT, Claude, Gemini, and Grok. Optimize with AI. Pick the winner. Refine further. All in one workspace built for people who take AI seriously.
Free plan available · No credit card required
Craft compelling product descriptions that highlight key benefits and drive conversions with clear, confident language.
Write product descriptions that speak directly to customer needs — concise, benefit-led, and built to convert.
Generate persuasive product copy that connects emotionally with buyers and clearly communicates value.
Write a product description for a noise-cancelling wireless headphone targeting remote workers.
Built for people who use AI seriously
Test Before You Ship
Run multiple prompt versions against the same input and see which performs best — before it ever touches production.
Optimize with AI
One-click prompt improvement with goal-based suggestions — clearer, more concise, more persuasive, or more structured.
Compare Any Model
Send the same prompt to GPT, Claude, Gemini, and Grok simultaneously. See every output side-by-side in one view.
Track What Wins
Race Stats show which models consistently outperform across all your test runs — so you know where to invest your prompts.
Everything you need to nail a prompt
Find the best phrasing fast.
Create multiple versions of the same prompt — different tone, structure, or approach — and run them side-by-side against the same test input. Pick the winner in seconds.
Stop rewriting the same prompt from scratch. Keep every version and compare them properly.
Write a product description for noise-cancelling headphones. Include key features and a strong CTA.
118 tokImagine putting on headphones and the world goes quiet. Write a product description that sells that feeling for our noise-cancelling headphones.
142 tokLead with the core benefit: silence on demand. Write a product description focused on the productivity gains of our headphones.
131 tokSame prompt. Different models.
Send one prompt version across GPT, Claude, Gemini, and Grok simultaneously. See every output in one view. No more switching tabs.
Different models excel at different tasks. Now you can actually prove which one works for yours.
From rough draft to refined prompt in one click.
The AI Optimizer improves your prompt based on a goal — clearer, more concise, more structured, more persuasive. Generate Variations produces 3 distinct rewrites instantly.
Great prompts are rarely written right the first time. Now improving them is effortless.
Write a good email to follow up with a sales lead. Be friendly and professional.
You are writing a follow-up sales email. Tone: professional and warm. Structure: 1) acknowledge last interaction 2) add value 3) clear CTA.
Keep the winner. Push it further.
After marking a winner, open a follow-up conversation thread directly from the winning output. Refine, extend, or redirect — with the original context already loaded.
Testing is only half the job. PromptLab lets you build on the best result without losing your place.
Your noise-cancelling headphones don't just block sound — they create space to think. With 40-hour battery life and adaptive ANC, they're engineered for the way you work.
Know which model wins your workflow.
Every time you mark a winner, PromptLab records it. Race Stats aggregates your wins across all test runs and shows you which models perform best for your specific use cases.
Data beats gut feeling. Race Stats turns your test history into real model intelligence.
How PromptLab works
Create a Prompt
Give your prompt a name and a home. One prompt = one use case or task.
Add & Improve Versions
Write prompt variants or use the AI Optimizer and Variations generator to improve them instantly.
Run Comparisons
Select versions and/or models, add a test input, and run. See outputs side-by-side.
Mark the Winner
Pick the best output. Continue the conversation to refine it further.
Track & Refine
Your history is saved. Race Stats show which models win most — and where to focus next.
Create a Prompt
Give your prompt a name and a home. One prompt = one use case or task.
Add & Improve Versions
Write prompt variants or use the AI Optimizer and Variations generator to improve them instantly.
Run Comparisons
Select versions and/or models, add a test input, and run. See outputs side-by-side.
Mark the Winner
Pick the best output. Continue the conversation to refine it further.
Track & Refine
Your history is saved. Race Stats show which models win most — and where to focus next.
You're already testing prompts.
Just not properly.
Most people test prompts by opening new chat windows, copying outputs into notes, and hoping they remember what worked. It's scattered, slow, and loses everything.
- ✕Juggling 10+ browser tabs across GPT, Claude, Gemini, Grok
- ✕Can't remember which phrasing actually worked
- ✕No way to properly compare two different prompts
- ✕Starting from scratch every single time
- ✕Zero visibility into which model wins for your use case
- ✕Losing good outputs because nothing is saved
- ✓One workspace for all your prompts and versions
- ✓Full run history — every output is saved automatically
- ✓Side-by-side comparison runner, built for this purpose
- ✓Version control so you never lose a good prompt
- ✓Race Stats show you exactly which models win
- ✓Continue any winning output in a follow-up thread
Simple, transparent pricing
Start free. Upgrade when you need more. No surprise charges.
Try PromptLab and learn the workflow.
No credit card required- ✓25 credits / month
- ✓Up to 5 prompts
- ✓Up to 20 saved prompt versions
- ✓Compare versions
- ✓Compare models
- ✓Prompt optimizer
- ✓Saved test inputs
- ✓Basic run history
For solo builders, marketers, and serious AI users.
- ✓500 credits / month
- ✓Unlimited prompts
- ✓Unlimited prompt versions
- ✓Compare versions & models
- ✓Prompt optimizer
- ✓AI variations generator
- ✓Follow-up conversations
- ✓Race Stats
- ✓Full run history
- ✓Priority access to new features
For agencies, heavy users, and advanced experimentation.
Best value- ✓1,500 credits / month
- ✓Everything in Pro
- ✓Higher usage for multi-model comparisons
- ✓More follow-up conversations
- ✓Deeper experimentation capacity
- ✓Early access to all new features
What are credits? 1 credit = 1 API call to any supported model. Running a prompt across 3 models costs 3 credits. Credits reset monthly and let you compare across providers without dealing with token math.
Stop guessing.
Start testing prompts properly.
Join the builders who've replaced scattered chat tabs with a structured, repeatable prompt testing workflow.
Free plan available · No credit card required