Cover letter

A cover letter is optional at most large employers and decisive at small ones. Where hiring is done by the person you'd report to rather than a recruiting team, it is often read before the resume and is the main thing separating two similar candidates. Where an ATS collects hundreds of applications a week, it may go unread — but an unread letter costs you nothing if you didn't spend an hour on it.

The version that works is specific and short. It names the role, states in one sentence what you'd be walking in able to do, gives one concrete piece of evidence for that claim, and says something about this employer that could not be copy-pasted to their competitor. Three to four short paragraphs. The version that fails restates the resume in prose or opens with how excited you are.

The tell that a letter was generated rather than written is usually structural, not stylistic: it praises the company in terms lifted straight from the About page, and it makes claims your resume doesn't support. Fixing that is a matter of grounding every sentence in something you actually did.