Guide 6 min read

Software Engineer Cover Letter Best Practices

Updated ApplyGen Team

Most software engineer cover letters get skipped, not because they’re badly written, but because they say the same thing. “I am a passionate developer with experience in…” is the opening of thousands of letters sitting in the same recruiter inbox. This guide covers what to write instead — and how to configure ApplyGen’s personalization settings so your defaults reflect these practices every time you generate.

Before you start

Step 1: Set your voice and tone for engineering roles

Open the extension, click the Settings icon, and go to the Personalize tab.

Under Voice & Feel, set:

Analytical voice is the right default for most engineering roles. It signals precision and suits a discipline where showing your reasoning matters. Add Confident to avoid the hedged, over-qualified phrasing that appears in a lot of AI-generated text.

For startup roles, swap Analytical for Bold. For developer advocacy, solutions engineering, or anything with a customer-facing component, Warm works better than either.

Step 2: Choose an opening hook that leads with output

Still in Voice & Feel, set Hook Style to Achievement-led.

This controls how the first sentence of your letter is framed. Achievement-led opens with something you built, shipped, or improved — not with a statement about yourself. The difference:

Before (story-driven):

“My journey into software started when I was fourteen and built my first website…”

After (achievement-led):

“In my last role I reduced our CI pipeline from 22 minutes to 6 by parallelising test suites — the kind of infrastructure work I’d want to continue on your platform team.”

The second version tells the reader what you do and why you’re relevant to them. It does that in one sentence.

Step 3: Configure emphasis and achievement style

Under Content Emphasis, set:

A quantified achievement style pushes the generated letter toward specifics: percentages, scale, time saved, error rates reduced. If your work doesn’t produce clean metrics — infrastructure, platform engineering, open-source — use Mixed, which blends numbers with narrative where available.

Avoid Narrative unless you’re applying to a role where the storytelling itself is being evaluated (developer relations, technical writing, engineering leadership). For most IC roles, specific numbers beat a well-told story.

Step 4: Add your technical skills list

In the Skills to Highlight field, paste the technical stack from the JD, then add two or three skills that differentiate you from a median candidate for the role.

Example for a backend role:

Go, PostgreSQL, Kubernetes, distributed systems, performance tuning

ApplyGen surfaces these in the letter body — they don’t just sit in a list, they get woven into the arguments the letter makes. Keep this list honest. If a skill appears here and nowhere in your resume, a hiring manager who interviews you will notice.

Step 5: Set word limit and structure

Under Structure, set:

Three short paragraphs is the right structure for most engineering cover letters. The three jobs those paragraphs need to do:

  1. Why this role at this company — the specific one, not any engineering job
  2. What you bring that’s relevant — concrete, not generic
  3. Short close — what you’re asking for, then stop

Under 350 words. Anything longer signals you’re not prioritising the reader’s time, which is exactly the wrong signal to send to an engineering team.

Step 6: Add an avoid-mentioning list

In the Avoid Mentioning field, enter:

passionate, team player, fast learner, synergy, love coding

These phrases appear in every letter and carry zero weight. A hiring manager at a company like Stripe or Linear reads hundreds of applications. “Passionate developer” tells them nothing they couldn’t infer from the fact that you applied. Cut it, replace nothing — the letter is better without it.

Add any other phrases that feel like filler to you personally. This list persists across all your generations until you change it.

Step 7: Address a real person

The default salutation is “Dear Hiring Manager.” It works, but a specific name works better. It signals you spent two minutes looking.

Before generating, search LinkedIn for the engineering recruiter or hiring manager listed on the role. Most job postings on LinkedIn surface the poster. Many Greenhouse and Lever postings link to a recruiter.

When you have a name, update the Salutation field to Dear [First Name], or Dear [First Name] [Last Name], — whichever reads naturally for the company’s culture.

If you genuinely can’t find a name after a reasonable search, leave the default. Don’t invent one.

Save these as a preset

If you’re applying to multiple engineering roles, save these settings as a named style preset so you don’t reconfigure them each time. In the Personalize tab, click Save as Preset, name it something like “Engineering — Standard”, and set it as active. You can create up to 5 presets and switch between them from the popup.

For a full walkthrough of the style presets system, see the ApplyGen Update v1.9.0: Style Presets and Advanced Personalization post.

If something goes wrong

The generated letter sounds too generic. Check that your resume is uploaded and that the Skills to Highlight field matches the specific JD — not a generic list of everything you know. The more specific the inputs, the more specific the output.

The opening line doesn’t reflect your strongest achievement. Switch Hook Style to Achievement-led if it isn’t already, then make sure your resume text includes the specific achievement you want foregrounded. ApplyGen pulls from your uploaded resume, so what’s in there shapes what comes out.

The letter is coming out too long. Verify your Word Limit is set to 250 and Length Structure is set to 3 short paragraphs. Both need to be set — word limit alone won’t enforce the structure.

ApplyGen says it can’t find a job description on the page. Some job boards render the posting dynamically. Try waiting for the full page to load, then clicking the extension icon again. If the posting is behind a login, make sure you’re signed in to the job site before opening the extension.

FAQ

Should I always include a cover letter when applying to engineering roles? No. Most ATS-first applications have a cover letter field that goes unread. Write one when the posting says it’s required, when you’re applying to a company small enough that a human reads first, when you have a referral to name, or when something about your background needs context — a career switch, a gap, a non-traditional path. Skip it when you’re applying through a large ATS with no prompt and no relationship.

My resume already lists my tech stack. Why repeat it in the cover letter? You’re not repeating it — you’re using it to make an argument. The resume says you know TypeScript. The cover letter says you used TypeScript to cut API response time by 40% at a company with the same scale as the one you’re applying to. Different jobs.

What if I don’t have metrics to put in an achievement-led opening? Most engineers undercount their metrics — check your commit history, pull request descriptions, and any post-mortems. If there genuinely aren’t numbers, use a specific deliverable instead: “Led the migration of a monolithic Django app to microservices” is concrete enough. Set Achievement Style to Narrative in ApplyGen if you’re consistently working without quantifiable outcomes.

How many style presets should I set up? Two is enough for most engineers: one for startups (Bold voice, Achievement-led hook, Confident tone) and one for larger or more traditional companies (Neutral voice, Professional and Formal tones, Standard closing). You can create up to 5 presets as a Google-signed-in user.

Is ApplyGen’s generated letter ready to send as-is? Treat it as a strong first draft. The one thing a generator can’t do is add the sentence that only you could write — a specific observation about the company’s product, a shared problem you’ve lived, a genuine reason you want this role over a competing offer. Add that before you send.

Get the settings right once, save them as a preset, and every letter ApplyGen generates starts from a position that’s already better than the median application. The rest is the one sentence that makes yours specific. ```

Common questions

Should I always include a cover letter when applying to engineering roles?
No. Most ATS-first applications have a cover letter field that goes unread. Write one when the posting says it's required, when you're applying to a company small enough that a human reads first, when you have a referral to name, or when something about your background needs context — a career switch, a gap, a non-traditional path. Skip it when you're applying through a large ATS with no prompt and no relationship.
My resume already lists my tech stack. Why repeat it in the cover letter?
You're not repeating it — you're using it to make an argument. The resume says you know TypeScript. The cover letter says you used TypeScript to cut API response time by 40% at a company with the same scale as the one you're applying to. Different jobs.
What if I don't have metrics to put in an achievement-led opening?
Most engineers undercount their metrics — check your commit history, pull request descriptions, and any post-mortems. If there genuinely aren't numbers, use a specific deliverable instead: 'Led the migration of a monolithic Django app to microservices' is concrete enough. Set Achievement Style to Narrative in ApplyGen if you're consistently working without quantifiable outcomes.
How many style presets should I set up?
Two is enough for most engineers: one for startups (Bold voice, Achievement-led hook, Confident tone) and one for larger or more traditional companies (Neutral voice, Professional and Formal tones, Standard closing). You can create up to 5 presets as a Google-signed-in user. See the v1.9.0 release notes for a full walkthrough.
Is ApplyGen's generated letter ready to send as-is?
Treat it as a strong first draft. The one thing a generator can't do is add the sentence that only you could write — a specific observation about the company's product, a shared problem you've lived, a genuine reason you want this role over the one at a competing company. Add that before you send.