Fernando
@francofernando.com
Software Engineer for 15+ years • Algorithms, Distributed Systems, System Design, Computer Vision • Dad & husband • I write http://polymathicengineer.com
The evolution of a web application architecture when going from serving hundreds to millions of users.
newsletter.francofernando.com/p/from-a-sin...
newsletter.francofernando.com/p/from-a-sin...
From a Single Server to Global Scale
The evolution of a web application architecture when going from serving hundreds to millions of users.
newsletter.francofernando.com
September 12, 2025 at 9:04 AM
The evolution of a web application architecture when going from serving hundreds to millions of users.
newsletter.francofernando.com/p/from-a-sin...
newsletter.francofernando.com/p/from-a-sin...
Be honest with yourself about what you want and work hard to get it.
Be meaningful and intentional with your time.
That is the only way to ensure that you give yourself the best odds.
Be meaningful and intentional with your time.
That is the only way to ensure that you give yourself the best odds.
August 31, 2025 at 2:54 PM
Be honest with yourself about what you want and work hard to get it.
Be meaningful and intentional with your time.
That is the only way to ensure that you give yourself the best odds.
Be meaningful and intentional with your time.
That is the only way to ensure that you give yourself the best odds.
When they hear "Don't Repeat Yourself," 99 out of 100 developers think of copy-paste code.
But DRY is about much more than that. The main focus is on knowledge, not code.
I wrote more about how to use DRY without falling into common traps here:
newsletter.francofernando.com/p/the-dry-pr...
But DRY is about much more than that. The main focus is on knowledge, not code.
I wrote more about how to use DRY without falling into common traps here:
newsletter.francofernando.com/p/the-dry-pr...
The DRY Principle
Why every software engineer should care about repetition: solutions that actually works.
newsletter.francofernando.com
August 29, 2025 at 11:27 AM
When they hear "Don't Repeat Yourself," 99 out of 100 developers think of copy-paste code.
But DRY is about much more than that. The main focus is on knowledge, not code.
I wrote more about how to use DRY without falling into common traps here:
newsletter.francofernando.com/p/the-dry-pr...
But DRY is about much more than that. The main focus is on knowledge, not code.
I wrote more about how to use DRY without falling into common traps here:
newsletter.francofernando.com/p/the-dry-pr...
We all go through 2 significant steps in our careers:
- Junior to mid-level developer
- Senior developer
In the first one, it matters more how well you code. "Nobody" will still listen to you.
But in the second stage and beyond, how well you communicate matters way more.
- Junior to mid-level developer
- Senior developer
In the first one, it matters more how well you code. "Nobody" will still listen to you.
But in the second stage and beyond, how well you communicate matters way more.
August 28, 2025 at 3:46 PM
We all go through 2 significant steps in our careers:
- Junior to mid-level developer
- Senior developer
In the first one, it matters more how well you code. "Nobody" will still listen to you.
But in the second stage and beyond, how well you communicate matters way more.
- Junior to mid-level developer
- Senior developer
In the first one, it matters more how well you code. "Nobody" will still listen to you.
But in the second stage and beyond, how well you communicate matters way more.
One thing I'm glad I paid a lot of attention to during my CS studies is "networking fundamentals".
Almost every project I've worked on has needed that background, and I've seen others who didn't have it have a hard time.
Almost every project I've worked on has needed that background, and I've seen others who didn't have it have a hard time.
August 26, 2025 at 2:39 PM
One thing I'm glad I paid a lot of attention to during my CS studies is "networking fundamentals".
Almost every project I've worked on has needed that background, and I've seen others who didn't have it have a hard time.
Almost every project I've worked on has needed that background, and I've seen others who didn't have it have a hard time.
Coding is way more interesting than sitting through meetings all day and writing down progress on a sheet
August 25, 2025 at 11:28 AM
Coding is way more interesting than sitting through meetings all day and writing down progress on a sheet
How do CDNs speed up content delivery on the internet?
You can read my in-depth article on how CDNs work under the hood and best practices when using them here:
newsletter.francofernando.com/p/a-critical...
You can read my in-depth article on how CDNs work under the hood and best practices when using them here:
newsletter.francofernando.com/p/a-critical...
A Critical Guide to Content Delivery Networks
How do CDNs work, and how to get the most benefits out of them.
newsletter.francofernando.com
August 22, 2025 at 9:11 AM
How do CDNs speed up content delivery on the internet?
You can read my in-depth article on how CDNs work under the hood and best practices when using them here:
newsletter.francofernando.com/p/a-critical...
You can read my in-depth article on how CDNs work under the hood and best practices when using them here:
newsletter.francofernando.com/p/a-critical...
If you work hard and are nice to people, you can get very far in life.
Being kind and honest to everyone is a skill that isn't given enough credit.
Being kind and honest to everyone is a skill that isn't given enough credit.
August 21, 2025 at 3:10 PM
If you work hard and are nice to people, you can get very far in life.
Being kind and honest to everyone is a skill that isn't given enough credit.
Being kind and honest to everyone is a skill that isn't given enough credit.
If you're not interested in your craft, you'll struggle to get a better software engineer.
Getting passionate isn't a gift, but a choice.
Pick a path, and get into it. Skills don't just come from a desire.
Getting passionate isn't a gift, but a choice.
Pick a path, and get into it. Skills don't just come from a desire.
August 19, 2025 at 2:46 PM
If you're not interested in your craft, you'll struggle to get a better software engineer.
Getting passionate isn't a gift, but a choice.
Pick a path, and get into it. Skills don't just come from a desire.
Getting passionate isn't a gift, but a choice.
Pick a path, and get into it. Skills don't just come from a desire.
Life is not at extremes but somewhere in the middle:
- Work out for 45 minutes instead of 3 hours
- Do deep work for 2-3 hours instead of 10
- Get 8 hours of sleep instead of 4
Take breaks, think, and live. We're humans, not robots.
- Work out for 45 minutes instead of 3 hours
- Do deep work for 2-3 hours instead of 10
- Get 8 hours of sleep instead of 4
Take breaks, think, and live. We're humans, not robots.
August 17, 2025 at 2:19 PM
Life is not at extremes but somewhere in the middle:
- Work out for 45 minutes instead of 3 hours
- Do deep work for 2-3 hours instead of 10
- Get 8 hours of sleep instead of 4
Take breaks, think, and live. We're humans, not robots.
- Work out for 45 minutes instead of 3 hours
- Do deep work for 2-3 hours instead of 10
- Get 8 hours of sleep instead of 4
Take breaks, think, and live. We're humans, not robots.
If you're in a system design interview, and you start brainstorming technical stuff, you're on the wrong path.
You're missing the most critical part of the design process: requirements.
I wrote about how requirements impact your design choices here:
newsletter.francofernando.com/p/requiremen...
You're missing the most critical part of the design process: requirements.
I wrote about how requirements impact your design choices here:
newsletter.francofernando.com/p/requiremen...
Requirements
Understanding system requirements in distributed system design.
newsletter.francofernando.com
August 15, 2025 at 8:56 AM
If you're in a system design interview, and you start brainstorming technical stuff, you're on the wrong path.
You're missing the most critical part of the design process: requirements.
I wrote about how requirements impact your design choices here:
newsletter.francofernando.com/p/requiremen...
You're missing the most critical part of the design process: requirements.
I wrote about how requirements impact your design choices here:
newsletter.francofernando.com/p/requiremen...
If you want to become a better programmer, there is no secret sauce.
You just need to spend a lot of time coding and building projects.
You just need to spend a lot of time coding and building projects.
August 14, 2025 at 3:13 PM
If you want to become a better programmer, there is no secret sauce.
You just need to spend a lot of time coding and building projects.
You just need to spend a lot of time coding and building projects.
Reposted by Fernando
Do you know what a database does most of the time?
This classic paper makes a very detailed profile of a transactional database, figuring out what each CPU command does.
Only 10% of the CPU instructions do critical work.
The rest are spread out fairly evenly between:
This classic paper makes a very detailed profile of a transactional database, figuring out what each CPU command does.
Only 10% of the CPU instructions do critical work.
The rest are spread out fairly evenly between:
August 13, 2025 at 11:39 AM
Do you know what a database does most of the time?
This classic paper makes a very detailed profile of a transactional database, figuring out what each CPU command does.
Only 10% of the CPU instructions do critical work.
The rest are spread out fairly evenly between:
This classic paper makes a very detailed profile of a transactional database, figuring out what each CPU command does.
Only 10% of the CPU instructions do critical work.
The rest are spread out fairly evenly between:
Do you know what a database does most of the time?
This classic paper makes a very detailed profile of a transactional database, figuring out what each CPU command does.
Only 10% of the CPU instructions do critical work.
The rest are spread out fairly evenly between:
This classic paper makes a very detailed profile of a transactional database, figuring out what each CPU command does.
Only 10% of the CPU instructions do critical work.
The rest are spread out fairly evenly between:
August 13, 2025 at 11:39 AM
Do you know what a database does most of the time?
This classic paper makes a very detailed profile of a transactional database, figuring out what each CPU command does.
Only 10% of the CPU instructions do critical work.
The rest are spread out fairly evenly between:
This classic paper makes a very detailed profile of a transactional database, figuring out what each CPU command does.
Only 10% of the CPU instructions do critical work.
The rest are spread out fairly evenly between:
Building something alongside your 9-5 job is rewarding, but it's important to have limits.
There will be times when your body will take breaks for you if you don't take breaks when you need them.
There will be times when your body will take breaks for you if you don't take breaks when you need them.
August 9, 2025 at 9:12 PM
Building something alongside your 9-5 job is rewarding, but it's important to have limits.
There will be times when your body will take breaks for you if you don't take breaks when you need them.
There will be times when your body will take breaks for you if you don't take breaks when you need them.
It took me 5+ years to become confident in my skills as a software engineer.
But I could have done it in less time if I had followed the 6 pieces of advice in the article below:
francofernando.substack.com/p/how-to-bec...
But I could have done it in less time if I had followed the 6 pieces of advice in the article below:
francofernando.substack.com/p/how-to-bec...
How to Become a Confident Software Engineer
Six critical steps to build your confidence as a software engineer.
francofernando.substack.com
August 8, 2025 at 8:30 AM
It took me 5+ years to become confident in my skills as a software engineer.
But I could have done it in less time if I had followed the 6 pieces of advice in the article below:
francofernando.substack.com/p/how-to-bec...
But I could have done it in less time if I had followed the 6 pieces of advice in the article below:
francofernando.substack.com/p/how-to-bec...
One thing people new to DSA often miss is that time complexity differs from speed.
O(N^2) algorithms can definitely outperform O(logN) algorithms for small input sizes.
O(N^2) algorithms can definitely outperform O(logN) algorithms for small input sizes.
August 7, 2025 at 5:29 PM
One thing people new to DSA often miss is that time complexity differs from speed.
O(N^2) algorithms can definitely outperform O(logN) algorithms for small input sizes.
O(N^2) algorithms can definitely outperform O(logN) algorithms for small input sizes.
I see many CVs from experienced engineers that put too much emphasis on their educational background.
But the truth is that once you get your first job, no one cares what school you went to.
Once you start building a small track record, things like your edu aren’t so important.
But the truth is that once you get your first job, no one cares what school you went to.
Once you start building a small track record, things like your edu aren’t so important.
August 5, 2025 at 4:56 PM
I see many CVs from experienced engineers that put too much emphasis on their educational background.
But the truth is that once you get your first job, no one cares what school you went to.
Once you start building a small track record, things like your edu aren’t so important.
But the truth is that once you get your first job, no one cares what school you went to.
Once you start building a small track record, things like your edu aren’t so important.
Every beginner in tech should know that nobody agrees on what a senior developer is.
Some people with less than 2 years of experience have the title.
At the same time, some do not have that title for 10.
Seniority at one company may not mean seniority at another.
Some people with less than 2 years of experience have the title.
At the same time, some do not have that title for 10.
Seniority at one company may not mean seniority at another.
August 4, 2025 at 4:58 PM
Every beginner in tech should know that nobody agrees on what a senior developer is.
Some people with less than 2 years of experience have the title.
At the same time, some do not have that title for 10.
Seniority at one company may not mean seniority at another.
Some people with less than 2 years of experience have the title.
At the same time, some do not have that title for 10.
Seniority at one company may not mean seniority at another.
Sunday morning mood 🌞 I love getting up early and feel the crashing of the waves and the sand on my feet when nobody is yet around.
August 3, 2025 at 7:38 AM
Sunday morning mood 🌞 I love getting up early and feel the crashing of the waves and the sand on my feet when nobody is yet around.
Design a URL Shortener is a popular interview question for many reasons.
It has a tricky algorithmic part for URL generation, and covers many aspects of how to scale a system, make it available, and design a data model.
Here is how to answer:
newsletter.francofernando.com/p/designing-...
It has a tricky algorithmic part for URL generation, and covers many aspects of how to scale a system, make it available, and design a data model.
Here is how to answer:
newsletter.francofernando.com/p/designing-...
Designing a URL Shortener
How to answer this popular system design question: from a simple concept to a scalable system.
newsletter.francofernando.com
August 1, 2025 at 8:04 AM
Design a URL Shortener is a popular interview question for many reasons.
It has a tricky algorithmic part for URL generation, and covers many aspects of how to scale a system, make it available, and design a data model.
Here is how to answer:
newsletter.francofernando.com/p/designing-...
It has a tricky algorithmic part for URL generation, and covers many aspects of how to scale a system, make it available, and design a data model.
Here is how to answer:
newsletter.francofernando.com/p/designing-...
When I started as a developer, I thought I had to know everything.
But I found out that was a fool's errand.
You can always learn new tech and find better ways to do things.
Do you need to know everything to be successful? Not at all.
But can you learn something new every day? Definitely.
But I found out that was a fool's errand.
You can always learn new tech and find better ways to do things.
Do you need to know everything to be successful? Not at all.
But can you learn something new every day? Definitely.
July 31, 2025 at 3:54 PM
When I started as a developer, I thought I had to know everything.
But I found out that was a fool's errand.
You can always learn new tech and find better ways to do things.
Do you need to know everything to be successful? Not at all.
But can you learn something new every day? Definitely.
But I found out that was a fool's errand.
You can always learn new tech and find better ways to do things.
Do you need to know everything to be successful? Not at all.
But can you learn something new every day? Definitely.
Storytelling is one of the best skills to have, both in interviews and in your daily work.
It makes it so much easier to establish empathic relationships with other people.
It makes it so much easier to establish empathic relationships with other people.
July 29, 2025 at 6:11 PM
Storytelling is one of the best skills to have, both in interviews and in your daily work.
It makes it so much easier to establish empathic relationships with other people.
It makes it so much easier to establish empathic relationships with other people.
Companies do not promote people for following the tickets.
They promote people who solve problems and add value to the business.
If you want to move up, ask yourself if you're only writing code or also solving problems.
They promote people who solve problems and add value to the business.
If you want to move up, ask yourself if you're only writing code or also solving problems.
July 28, 2025 at 1:29 PM
Companies do not promote people for following the tickets.
They promote people who solve problems and add value to the business.
If you want to move up, ask yourself if you're only writing code or also solving problems.
They promote people who solve problems and add value to the business.
If you want to move up, ask yourself if you're only writing code or also solving problems.
Software engineers spend at least 20% of their time reviewing code.
But many of them don't know what to focus on.
They randomly scan code changes, rather than having a structured approach.
Here is what to look for in the right priority:
newsletter.francofernando.com/p/what-to-lo...
But many of them don't know what to focus on.
They randomly scan code changes, rather than having a structured approach.
Here is what to look for in the right priority:
newsletter.francofernando.com/p/what-to-lo...
What to Look for in Code Reviews
A detailed guide on what to focus on as a reviewer during pull requests.
newsletter.francofernando.com
July 25, 2025 at 9:08 AM
Software engineers spend at least 20% of their time reviewing code.
But many of them don't know what to focus on.
They randomly scan code changes, rather than having a structured approach.
Here is what to look for in the right priority:
newsletter.francofernando.com/p/what-to-lo...
But many of them don't know what to focus on.
They randomly scan code changes, rather than having a structured approach.
Here is what to look for in the right priority:
newsletter.francofernando.com/p/what-to-lo...