Developer builds offline cold email scorer in single HTML file, no dependencies

A B2B sales writer frustrated by vague cold-email advice built a deterministic email scoring tool packed into a single 220-line HTML file with no frameworks, APIs, or external dependencies. The tool accepts a subject line and body, then returns a score out of 100 across eight measurable checks including subject length, spam phrases, word count, readability, and call-to-action detection. The developer deliberately avoided AI model calls to ensure identical inputs always produce identical outputs and to eliminate privacy concerns around real sales emails. Every scoring threshold — such as a subject line ceiling of 55 characters and a body word count sweet spot of 50 to 150 — was manually justified and documented rather than delegated to a black-box model. The project is publicly available on GitHub under an MIT license.