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v1.7 — Library export · Evaluate timeline · Quick resume

Every prompt, sharpened.

The multi-provider workspace for prompt engineering. Enhance, compare, and iterate across Claude, GPT-4o, Gemini, and local models — then ship with confidence.

Improve your first prompt See it in action
7
Enhancement modes
5
AI providers
100%
Local storage
0ms
Data sent to us
Capabilities

One workspace.
Every tool you need.

Prompt Lab packs a full prompt engineering toolkit into a single interface — no tab switching, no copy-pasting between tools.

Enhance

Sharpen clarity without changing intent

Seven enhancement modes transform rough ideas into precision prompts. Improve structure, expand detail, clean noise, or tighten focus — all while preserving your original meaning.

  • Improve, Expand, Shorten, Fix, Simplify, Formalize, and Custom modes
  • Word-level diff view shows exactly what changed and why
  • One-click accept or iterate further
enhance mode
Improve
Expand
Shorten
Fix
Original
Enhanced
Compare

A/B test across any model

Send the same prompt to two different providers and see the responses side-by-side. Find the right model for every use case — without leaving the workspace.

  • Claude, GPT-4o, Gemini, OpenRouter, and Ollama
  • Side-by-side response comparison
  • Evaluate and track results over time
a/b compare
Claude 3.5 Sonnet
Anthropic
GPT-4o
OpenAI
Gemini 1.5 Pro
Google
Llama 3.1 70B
Ollama (local)
Library

Save once, use everywhere

Build a personal library of battle-tested prompts. Tag, search, and compose from your best work. Export to JSON anytime — your prompts belong to you.

  • Full-text search across your entire library
  • Compose complex prompts from saved fragments
  • JSON export for portability and version control
prompt library
Code Review System Prompt
engineering · saved 2d ago
1.2k tokens
Email Tone Matcher
writing · saved 5d ago
840 tokens
Data Analysis Chain
research · saved 1w ago
2.1k tokens
API Documentation Generator
engineering · saved 2w ago
960 tokens
Try it

See the difference in real time

Paste any rough prompt and watch Prompt Lab transform it.

prompt lab
Your prompt
Enhanced
⌘ + Enter to enhance
And more

Everything else
you'd expect.

Chrome & Vivaldi Extension
Enhance prompts directly inside ChatGPT, Claude, or any AI interface. The side panel keeps your workflow in context — no tab switching required. Works on Chrome, Vivaldi, Brave, and Edge.
Prompt Composer
Build complex prompts from reusable fragments. Chain system prompts, context blocks, and instructions into composable templates.
PII Scanner
Catch personal data before you send. Automatic detection and optional redaction of names, emails, phone numbers, and more.
Prompt Linting
Automated quality checks flag ambiguity, missing context, and common anti-patterns before you hit send.
Scratchpad
A distraction-free workspace for drafting, brainstorming, and iterating on prompts before you commit.
Eval History
Track every test run with timestamps, model versions, and scored results. See how your prompts improve over time.
Pricing

Start free. Scale when ready.

No credit card required. Your prompts stay local — always.

Free
$0
Forever free
  • All 7 enhancement modes
  • Multi-model provider switching
  • Prompt library with search
  • Chrome extension
  • 100% local storage
Get started free
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Pro
$9
per month
  • Everything in Free
  • A/B Compare with eval scoring
  • Prompt Composer templates
  • PII scanner + auto-redaction
  • Advanced linting rules
  • Priority support
Get Pro →
Annual
$100
per year — save $8
  • Everything in Pro
  • 2 months free
  • Early access to new features
  • Roadmap input
Go annual

Your prompts deserve
better.

Join thousands of engineers, writers, and researchers who ship better AI — starting with better prompts.

Try Prompt Lab free