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Define the standard.
Quantify the performance.
Auto-optimize the result.

Stop guessing. Set your custom evaluations for what "good" looks like, get hard scores across every model, and let our engine automatically rewrite your prompts to beat your own benchmark.

Join the Waitlist See Features
Early Access
10+ Models Supported
Custom Evaluations

Without Spring Prompt

Your Prompt
Write a compelling email to convince {{user}} to upgrade to our premium plan. Be persuasive and highlight the key benefits. Make it feel personal and urgent.
Feedback
PE
Prompt Engineer 2:34 PM

Hey, can someone review this upgrade email output before I ship it? 👀

CEO
CEO
CEO 2:41 PM

Looks okay I guess? 🤷 Tone might be off, not sure about the CTA. Let's just ship it and see.

😕 🤷
❌ No way to measure ❌ Subjective feedback ❌ Ship and pray

With Spring Prompt

Define Evals ✓
Benchmark ✓
Optimize ✓

Watch the magic happen...

Tone Professional yet warm
Persuasiveness Creates urgency
CTA Strength Clear next step
Benchmarking prompt Running evals... Complete
Write a compelling email to convince {{user}} to upgrade...
Tone
Persuasiveness
CTA Strength
Overall Score
5.2/10
Rewriting... Prompt changes Iteration /5
prompt.txt + −
Analyzing & rewriting...
Score Progress
/10
10 0
12345
Evaluations Scoring...
Tone
Persuasiveness
CTA Strength
Overall
/10
Optimized Prompt +77% improvement
Write a personalized upgrade email to {{user_name}}.
Reference their {{recent_activity}}. Focus on {{top_3_features}}.
Include 48h offer: {{discount_code}}. End with CTA: {{cta_button_text}}.
Tone: helpful advisor, not salesperson.
Conditional logic based on {{user_plan}}
Tone
9.2
Persuasiveness
8.8
CTA Strength
9.5
Overall Score
9.2/10
✓ Measurable ✓ Auto-optimized ✓ 5 iterations

Stop guessing. Start optimizing.

Spring Prompt gives you everything you need to ship better prompts, faster.

Define "Good"

Create custom evals that match your exact quality bar

Measure Everything

Get hard scores instead of gut feelings

Auto-Optimize

Let AI rewrite your prompts to beat your benchmark

Ship Faster

Go from idea to production-ready in minutes

Join the Waitlist

Early access launching soon

Everything You Need

Professional tools for prompt engineering, all in one platform

Custom Evaluations

Create evaluation criteria specific to your use case. Test for accuracy, tone, format, and any custom metrics you need.

Model Comparison

Test your prompts across GPT-4, Claude, Gemini, Llama, and more. Find the best model for your specific use case.

Data-Driven Insights

Track performance over time, compare versions, and make decisions based on real evaluation data.

Prompt Lab

Experiment with prompt variations, test different approaches, and iterate quickly with our prompt studio.

Test Data Management

Organize and manage your test cases. Build comprehensive evaluation sets for thorough testing.

Version Control

Track prompt versions, compare changes, and roll back when needed. Never lose a working prompt again.

How It Works

Get started in minutes, not hours

1

Create a Project

Set up your prompt project in seconds. Add your prompt and any context variables.

2

Define Evaluations

Create custom evaluation criteria or use our templates. Define what "good" looks like.

3

Run Tests

Test across multiple models and scenarios. Get detailed results and comparisons.

✓

Optimize & Deploy

Use insights to improve your prompts. Deploy with confidence.

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Simple, Transparent Pricing

Choose the plan that fits your needs. Credits are used for LLM API calls during evaluations.

Most Popular

Starter

$19.99 /month

5,000 credits/month

  • Unlimited projects
  • 5,000 credits included
  • Custom evaluations
  • 10+ AI models
  • Priority support
Join Waitlist

Pro

$99.99 /month

50,000 credits/month

  • Everything in Starter
  • 50,000 credits included
  • Advanced analytics
  • Team features (coming soon)
Join Waitlist

Need more credits? Top-ups available from $5.50 for 5,000 credits. Credits never expire.

Frequently Asked Questions

Everything you need to know

Credits are used to pay for LLM API calls when running evaluations. Each credit roughly equals one API call. This way, you don't need your own API keys for multiple providers.

We support 10+ models including GPT-4o, Claude 3.5, Gemini, Llama, and more. All API access is included in your credits - no separate API keys needed.

We support all major providers including OpenAI (GPT-4, GPT-4o, GPT-3.5), Anthropic (Claude 3.5, Claude 3), Google (Gemini Pro, Gemini Flash), and open-source models via providers like Together AI and Groq.

Spring Prompt focuses on practical prompt engineering workflows. We combine custom evaluations, multi-model comparison, and version control in one tool. Built by prompt engineering practitioners who understand real-world needs.

Monthly subscription credits reset each billing cycle. However, any credits you purchase as top-ups never expire and roll over indefinitely.

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Expert insights on AI prompt engineering, optimization techniques, and best practices.

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