Do Developers Need a Cover Letter? (And How to Write One That Works)

Ask ten engineers about cover letters and you'll get ten answers, most of them dismissive. The honest position is somewhere in the middle: a generic cover letter is worthless and occasionally harmful, while a short, specific one is one of the cheapest advantages available in a competitive process. The difference is entirely in whether it could have been sent to any other company.

When it's worth writing one

Write one when:

• The application form has a message field. Leaving it blank next to candidates who filled it in is a needless handicap.
• You're changing direction — different stack, different domain, career switch, returning after a gap. Your CV raises a question; the letter answers it before anyone has to guess.
• You genuinely know the product or have used it. This is the strongest possible opening and almost nobody has it.
• It's a small company or a startup. Founders read these. At small companies, the letter is frequently the deciding factor between two similar CVs.
• The post asks for one, obviously — including as a filter for people who follow instructions.

When it doesn't matter

Skip it, or keep it to two lines, when:

• You're applying through a large company's automated system where it's optional and likely unread.
• A recruiter is submitting you and a conversation has already happened.
• You have a referral. The referral does the work a cover letter attempts.
• The role is an exact match for your CV and there's nothing to explain.

The cost of a generic one isn't zero: reviewers notice a letter clearly written for a different company, and it undermines the CV attached to it.

What hiring managers actually want to know

Whoever reads it is trying to answer three questions quickly:

1. Why this job? Not "why a job" — why this one, at this company.
2. What's the evidence you can do it? One concrete example beats every adjective.
3. Is there anything my process would misread? Gaps, switches, an unusual background.

Everything else is filler.

A structure that works

Keep it under 200 words. Four short paragraphs.

Paragraph one — why this company, specifically. Name something real. What the product does, a technical decision they wrote about, a problem you know is hard from their space. "I've used [product] for two years and the [specific feature] is what got me interested in how you handle [technical problem]" is worth more than any statement of enthusiasm.

Paragraph two — your single most relevant piece of evidence. One project, with a result. What you built, the constraint you worked under, what happened. Numbers where they're honest. This is the paragraph that earns the interview.

Paragraph three — the thing your CV doesn't explain. The stack switch, the gap, the reason a backend engineer is applying for a platform role. One or two sentences, stated plainly, no apology. If nothing needs explaining, delete this paragraph.

Paragraph four — a clean close. What you'd like to happen next, and a link to something they can look at.

An example, in outline

I've been using [product] since [when] — the [feature] is the reason my team stopped building our own [thing]. I saw you're working on [problem], which is close to what I spent the last two years on.

At [company] I owned [system] through [constraint — a migration, a growth phase, a rewrite]. [What changed: latency, cost, reliability, delivery time.] The hardest part was [genuine difficulty], and I'd be happy to walk through how we approached it.

You'll notice I've mostly worked in [X] and this role is [Y]. I moved deliberately: [one-sentence reason], and I've been building [evidence] in that direction.

Happy to talk any time. Here's [something they can look at].

That's it. Nobody wants a page.

Mistakes that cost you interviews

• Opening with "I am writing to apply for the position of…" Every reviewer has seen this ten thousand times. Use the first line to say something only you could say.
• Restating your CV in prose. They already have it, attached, right there.
• Describing yourself with adjectives. "Passionate, detail-oriented team player" is unfalsifiable and therefore ignored. Show the trait through an example or leave it out.
• Length. A full page is not thoroughness; it's a signal you can't prioritize.
• Forgetting to change the company name. It happens constantly and it ends the application.
• Explaining a gap defensively. One straightforward sentence closes the topic. Three anxious paragraphs open it.
• Letting a language model write the whole thing. Reviewers now recognize the register instantly, and the generic result is precisely the failure mode you're trying to avoid. Use it to tighten your own draft, not to generate one.

The takeaway

A cover letter is worth writing exactly when you have something specific to say: you know the company, you have one strong piece of evidence, or your CV raises a question worth answering first. Keep it under 200 words, lead with something only you could have written, and attach something they can look at. Skip it entirely rather than send a generic one — a template letter costs you more than no letter at all.

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