Build an Email Open Rate Calculator with Claude Code
Email marketing analytics tool that calculates open rates and campaign performance metrics. Email marketers and campaign managers use it to measure engagement and optimize email strategies.
The Claude Code prompt
Build an Email Open Rate Calculator web app. People search for "email open rate calculator" about 150 times a month, plus related searches like "email marketing calculator", "open rate calculator", "email metrics calculator". The goal is a tool that ranks for those searches and makes money. What it should do: Create an email open rate calculator with campaign data inputs (sent, opened, clicked). Calculate open rate, click-through rate, and engagement metrics. Include industry benchmarks, improvement suggestions, and trend analysis. Add A/B testing calculator and ROI analysis. Focus on getting basic rate calculations working first. How to build it: 1. Read this folder first. If it is empty, set up Next.js (App Router, TypeScript, Tailwind). Write a short PLAN.md with the pages, components, any library or API you need, and what you are leaving for later. Then build. 2. Put the tool itself on the homepage so a visitor can use it within seconds, with no sign-up. Do the processing in the browser where you can, so it is fast and cheap to run. Look at how Mailchimp, Constant Contact, Campaign Monitor do it and make ours simpler and faster. 3. Make it rank. Use "email open rate calculator" in the title tag, H1 and meta description. Under the tool, add a short how-to and an FAQ with FAQPage schema, and add a sitemap and robots.txt. Scaffold these programmatic pages from one template and a data file: /email-open-rate-[industry], /email-metrics-[business-type], /campaign-calculator-[email-type]. 4. Monetisation: Freemium: 10 calculations/month, $8/mo unlimited + benchmarks. Add a pricing page and the free usage limit, and leave Stripe checkout as a clearly marked stub with the environment variables it needs. 5. Run it locally and test the main flow end to end, including edge cases like empty input and very large files. Fix what breaks, then finish with a summary of what works, what is stubbed and how to deploy it to Vercel.
Paste it into Claude Code in an empty folder. It plans first, so read PLAN.md and steer before it starts building.
What people search for
Who you're up against
- Mailchimp : Email marketing platform with analytics
- Constant Contact : Email marketing service with reporting
- Campaign Monitor : Email marketing platform with metrics
Pages that can rank
One template, many long-tail pages:
- /email-open-rate-[industry]
- /email-metrics-[business-type]
- /campaign-calculator-[email-type]
- /email-analytics-[company-size]
Content to write
- How to Calculate and Improve Email Open Rates
- Email Marketing Metrics Every Marketer Should Track
- Email Open Rate Benchmarks by Industry
- Email Campaign Optimization Using Performance Data
How it makes money
Freemium: 10 calculations/month, $8/mo unlimited + benchmarks
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