TailorLetter
Most software engineers write terrible cover letters. Not because they can't write, but because they treat the cover letter like a second CV, listing technologies and frameworks instead of explaining what they actually built and why it mattered.
Here are three real examples that work, with an analysis of what makes each one effective.
What makes a software engineer cover letter good
Before the examples: the same principles apply regardless of level.
- Specific over generic. "I have experience with distributed systems" is weak. "I rebuilt our event pipeline to handle 10x traffic after a viral launch" is strong.
- One concrete achievement, not a list. Hiring managers read dozens of letters. One story that sticks beats five bullet points that blur together.
- Show you understand the company. Not "I've always been passionate about your mission", something that proves you've actually looked at what they're building.
- Short. Under 300 words. Engineers are busy. So are the people who hire them.
Example 1: Junior developer (first job)
I've been watching Mono's approach to embedded finance since you launched the API-first banking product last year. What caught my attention wasn't the product itself, it was a thread your CTO posted about the tradeoffs you made choosing Postgres over a time-series DB for transaction data. That kind of thinking is what I want to learn from.
During my final year project I built a payment reconciliation tool for a local NGO using Node and PostgreSQL. It's nothing close to production scale, but it taught me what breaks when you're reconciling 10,000 rows with inconsistent timestamps, and how to write queries that don't time out at 2am. I've kept contributing to it since graduating.
I'd love to explore whether there's a fit. I'm a fast learner and willing to do the unglamorous work that keeps systems running.
Why it works: It doesn't apologize for being junior. It shows genuine company research, explains a real project with real constraints, and closes with honesty instead of hype.
Example 2: Senior engineer
Your infrastructure team posted about migrating to a multi-region setup last quarter. I've been there and I know the part they didn't write about: the six weeks of debugging subtle clock drift issues after the migration was "done".
At my current company I led the move from a single-region monolith to a multi-region microservices architecture for a platform processing $2M/day in transactions. The migration took 14 months and required zero downtime. The hard part wasn't the technical design, it was building the tooling that let the team deploy confidently across regions without understanding every piece of the stack.
I'm interested in what you're building next. Happy to get into specifics on a call.
Why it works: It opens with something that shows deep familiarity with the company's actual work. The achievement is specific ($2M/day, 14 months, zero downtime) and focuses on the organizational challenge, not just the technical one. The close is confident without being arrogant.
Example 3: Career change into tech
I spent six years designing fluid systems for industrial equipment. For the last two, I've been translating that into code. Specifically, building simulation tools in Python that our team used to model heat transfer in battery packs before committing to physical prototypes. It saved us an estimated $300K in prototyping costs and three months of iteration time.
I'm making a deliberate move into software engineering, and I chose to focus on climate tech because the problems are harder and the stakes are higher. Your work on battery degradation modeling is directly in the intersection of what I know and what I want to learn.
I'd welcome the chance to show you what I've built and talk through how my background could be useful on your team.
Why it works: It leads with the most impressive thing (quantified impact), doesn't apologize for the non-traditional background, and makes the career change feel intentional rather than desperate. The company-specific connection is substantive, not flattery.
Common mistakes in software engineer cover letters
- Listing technologies: "Proficient in React, Node.js, Python, AWS, Docker, Kubernetes..." → this belongs in the CV, not the cover letter.
- Starting with "I am writing to express my interest in...": This tells the reader nothing and wastes the first sentence.
- Explaining what the company does: They know what they do. You're wasting space.
- Vague claims: "I have a passion for writing clean, scalable code" → every candidate says this.
Generate a tailored cover letter in under a minute
Paste the job description, upload your CV, and TailorLetter writes a cover letter that highlights the experience that actually matters for that specific role.
Try it freeFrequently asked questions
Do software engineers even need cover letters?
Depends on the company. Big tech companies with high-volume recruiting often skip them. Startups and companies hiring for specific roles frequently read them. When in doubt, write one. A good one takes 15 minutes and can make a real difference.
Should I mention my GitHub or portfolio?
Yes, but briefly. One link, in context ("you can see the project I mentioned at github.com/..."). Don't ask them to review your entire portfolio as part of the application.
How technical should the cover letter be?
Technical enough to show you know what you're talking about, not so technical that a non-engineer can't follow it. If only 20% of readers will understand a sentence, cut it.