I am a quite good bad programmer

152 points by caviv ↗ HN
I find somethings actually strange. Per se, checking my quality as a developer with job interview questions I will receive a not so high grade. I would say between 5 to 7 out of 10. Not brilliant. But as a developer I think I am actually really good.

I never "studied" computer science in a regular way, but I am in the industry more than 20 years. I started as a hacker, reverse engineering, assembly code, moved to C and C++ and now web development in Node.JS, Go (golang) and Rust and Vanilla JS. Touched of course Python and Arduino and Raspberry PI.

I find it that my code and overall look as much better (if I can be a bit non modest for a second) than other developers even seniors.

- My code is highly readable with good comments and other can take over my code responsibility quite easily

- My code runs (and also complies) faster than other - I understands the usage of Hash / Map instead of searching arrays and many other small things that actually enhance the code performance

- I know how to KISS (Keep it stupid and simple) and so I am able to write complicated software because the basic is simple and separated so my feasible to comprehend

- I understands Object Oriented correctly and knows where to use it and how and when to avoid it

- I know not to search always the latest new shiny thing (library or framework) and use legacy software that actually do the job when needed without complications

- I understand how the computer works, from BIOS, BUS to OS (Linux and Windows internals)

- I have (again if I may say) good product skills and some UX guts which helps me manage things on my own

All of this together allowed me to build and sell already two startups. Develop and maintain easily many web sites and SaaS which creates me nice passive income (such as https://gematrix.org).

So am I a good or bad programmer? - Still I will score quite low in job interview questions ...

159 comments

[ 4.6 ms ] story [ 377 ms ] thread
It's difficult for any of us to really tell how much truth is in every statement. For example readability - its difficult to asses it without looking at your code.

It's nothing personal, but many developers tend to think about their skills higher than they are in reality.

What i can suggest you, is to ask for feedback after interviews. You will get more specifics there

EDIT: I forgot to actually add a verb in the first sentence and some punctation

Maybe better to do mock interviews if you can? Lots of places won't give any feedback on no-hires for legal liability reasons.
Don't take seriously any feedback you get from an interview. Unless you already trust someone involved in the process.
I was going to comment something about how with modern tooling a lot of people (including me) can write working apps without being too advanced but from your description it sounds like you know quite a lot.

I don't think you have to take the label "bad programmer" because you don't ace job interviews. Those are contrived games anyway, if you practice you can learn to ace them but from your position it doesn't sound nessecary.

I'll also throw out that it's not binary in the other direction either.

There is always more to learn and as long as it's still fun I find that reading one more technical book usually does add value somewhere I wasn't expecting.

You're "expected" to study for job interview questions. It's more a measure of willingness to jump through hoops than your competence. Developer interview questions in general has little to do with what you'll do as a developer, and what you're expected to know as a developer.
This is so weird. Aren’t you just selecting for obedience and unnecessary hoop jumping? It seems like this would also select the kind of engineers who aren’t willing to say “no, that’s a dumb approach, we shouldn’t do that, here’s an alternative”?

When I was a Junior dev one of the first lessons my boss taught me was to always always speak up if something looked off to me. Maybe I’d get an explanation and be enlightened or maybe I’d actually sniffed out a mistake or code smell. It always seemed like a win win.

But if the entire job is based on “here swallow this bullshit pill before you’re let in the door”, isn’t it going to be hard to get the devs who are allergic to bullshit?

> It seems like this would also select the kind of engineers who aren’t willing to say “no, that’s a dumb approach, we shouldn’t do that, here’s an alternative”?

This is exactly the reason why any big enough company is eventually going to s*hit

And why founding team doesn’t stay long in a successful startup.

> And why founding team doesn’t stay long in a successful startup.

Doesn't the founding team get to determine the hiring practices?

There's only 24 hours in a day.
Well sure, but one would expect the founding team to do the early interviews, and then setup the process that's followed by later hires, no? Also, I would have thought that hiring would pretty much top priority. The employees make or break a company.
Business processes and traditions are not a source code. It always changes and evolves with people and millions other factors.

One of the factors — it’s too risky for a big company not to hire based on obedience.

It's not that they have much choice once company grow in complexity beyond something that a small group of people can possibly handle.
> isn’t it going to be hard to get the devs who are allergic to bullshit

Maybe that’s what they want, namely a self selection of devs who will be happy and okay inside an org that is filled with bullshit.

Tech interviews are optimised for big tech. Those devs won't care so much when you slap 3x total compensation on their ass.
> This is so weird. Aren’t you just selecting for obedience and unnecessary hoop jumping?

Mostly it selects for people who can turn this on when needed, which honestly is a critical skill. Sometimes life is just bullshit, either you're a person who makes that easier for everyone or you're a person who makes that harder for everyone. But an inability to get past it is a red flag.

Example: I work in medical devices, a regulated space. My job is 50% normal software engineering, and 50% dealing with BS regulations. It's part of the job. You can get annoyed at it, but it won't go away, and the job can be very fulfilling if you can get past the BS part.
How many devices do you see or design have implicit state in the software controlling them?

(if it is not explcitly defined, and there is state based behaviour, it is by definition then implicit)

At the moment I'm trying to overcome the inertia on this issue in the general process/industry sector with child standards from IEC 61508 - 61511 and 62061.

I am guesssing you apply the medical standards IEC 60601?

Or at design of devices at component level then IEC 61508?

Interested to know how it fits in to the overall Functional Safety approach.

I work on software as a medical device, so I have no idea about hardware safety controls. I have to deal with change control boards and approval matrices for every new build we push, though.
> obedience and unnecessary hoop jumping

This is what makes you successful in some large organizations, unfortunately.

> Aren’t you just selecting for obedience and unnecessary hoop jumping?

Let's be real, that's exactly what most mid+ companies are looking for.

> It's more a measure of willingness to jump through hoops than your competence.

I'd say it's more a measure of how well you can learn an arbitrary skill. They could change it to solving Sudoku puzzles, grading SAT essays, or wood carving and most of the same people who do well in leetcode interviews would pick up those skills and ace the interviews.

But you don't need arbitrary skills, you need solid development skills to do the job. So they're always going to miss out on people who aren't good at learning arbitrary skills but already have solid development skills. But many big companies seem alright with that tradeoff.

You're also biasing towards the type of person who is ok with either burning themselves out or skiving off work (or both) to get good at these types of interviews.
> I'd say it's more a measure of how well you can learn an arbitrary skill.

Time is finite. You can learn to write better programs, or grind Leetcode. Leetcode interviews favor the one who can put enough time on the latter.

A better explaination is it's a chain reaction. People who know only to Leetcode enter the industry, and ask only Leetcode questions.

Not quite. Learn more about Monad and Category theory then i'm sure you're really a good programmer.
Job interviews have a very questionable form of gatekeeping. But it is a very well documented form of gatekeeping. If you want to get good grades at job inteviews, you can practice how to pass that test... I do agree it doesn't reflect the quality of developer you are, but it is what it is...
> But it is a very well documented form of gatekeeping.

"Tell me your opinion of the emperor's apparel."

Doing well at interviews has low correlation with being good at the job, simple as that.
I would say that even being demonstrably good at the job has an imperfect correlation with being productive on the job. Because people lose motivation and procrastinate.

A given programmer might blaze through an interview task like a superstar, yet take two days to get started on it if it's an actual job assignment.

Everyone can put on their Gets Shit Done hat in an interview, in other words

That is why interviewers ask questions about previous job experiences and contact references.

> Doing well at interviews has low correlation with being good at the job, simple as that.

That's true, but only because companies are bad at interviewing. It is possible to do much better than companies typically do at this. It's just a really hard skill to master, and involves more than just standardised testing.

A kinder rephrasing of "companies are bad at interviewing" would be that finding out who is a good fit for a company (and vice versa) is a very difficult problem, more so given the resource constraints.
if what u say is truth then you are undoubtedly a good programmer - pragmatic people who are thoughtful of others (users and maintainers) are clearly good.

this is the bizarre thing - these are qualities that actually make a good product developer, but many companies pretend that they are hiring people who will be coming up with new algorithms and not just make db records when someone clicks or submits a form.

While not as profound as you, I think I'm a decent developer. The caveat being that I don't work in software development, but in a role that's on the business side with a mix of management, software engineering, a bit of maths and data engineering and analysis.

A few years ago I was applying to a well-known consulting firm, a role in data analytics. I got rejected due to "not knowing SQL" (which at that point I've used professionally for 8 years) and they hired someone else. A few months later, the same company made me an offer for another team in a more business driven role. I've ended up as a lead solution architect for a pretty involved WASM-based product with them and managing the guy they hired instead of me before. The guy couldn't code a for-loop in Python and I ended up doing all the engineering work for him until we could offboard him.

Moral of the story: perceptions, culture, and internal team politics might play a way bigger role in seeing your value as an engineer than we might acknowledge.

(comment deleted)
> My code is highly readable with good comments and other can take over my code responsibility quite easily

Say no more, you're hired.

Remarks like "my code is highly readable", "my code has good comments", "my code runs faster", "my code is simple and separable", ... mean nothing unless your code is read by someone else and compared to code written by another competitive programmer (YouTube and Udemy tutorials usually don't fall here).
World needs more 1x programmers.
OP seems more of a 10x dude IMHO
My fear is, I see many 0.5x programmers / workers who are active drag on products and teams. :-/ The problem with these workers are, the more you have these people on the team, it has a multiplying effect instead of additive in terms of productivity. 0.5x0.5x0.5 (not 0.5+0.5+0.5)
I would say it is a range from 0.1-1.0,10

Companies need those 10xdevs because they are bloated with dead weight.

But office politics make it very hard to cut that dead weight.

If most of the team are actually 0.1s then a 1 will seem like a x10.

Anyway, I've worked with plenty of people who can get stuff done, and I've been able to get stuff done myself sometimes. However, it's all relative and if I'd been at Xerox Parc in the 70s I'd have been a 0.001 for sure.

Strong agree. I'm a big fan of https://1x.engineer and pretty much everything it lists. To pick a few:

>Copy/pastes code snippets from Stack Overflow, Glitch, Codepen, or wherever they find answers.

>Gives credit where credit is due.

>Spends time on things outside of engineering, like hobbies, friends, and family.

>Doesn't act surprised when someone doesn’t know something.

>Willing to admit when they're wrong, and aren't afraid to say "I don't know."

>Doesn't riddicule entire professions within engineering, especially not when in a position of leadership.

> I understands the usage of Hash / Map instead of searching arrays and many other small things that actually enhance the code performance

I would consider this an assumed skill for any developer with a college degree. It’s basically the point of the entire Data Structures class, which is a degree requirement.

Optimistically, you should definitely be able to assume this. In practice, though, I wouldn't. I've been in school with and interviewed many a college grad that had virtually no concept of how to effectively apply any of the data structures they "learned". It's definitely not a given
I had an extraordinarily painful conversation with someone who had done pretty well in our DS class but didn’t have a ton of practical experience.

Me: “why don’t you just use a hash table here? That array you’re iterating through each time has like 200,000 entries”

Him: “I can’t. I need to be able to get both the key and the value and hash tables don’t store the key”

Me: “…sigh, school has failed us again”

I had an extraordinarily painful conversation with experience programmers when I pointed out that the values that the hash key relyed upon must not change, for the life of the hash map.
> ...when I pointed out that the values that the hash key relyed upon must not change, for the life of the hash map.

Now I'm wondering about something like:

  MutableHashMap<MutableKey<T1>, Value<T2>>
You could probably have they key be a container object and allow changing its internal value, which would then communicate to the hash map that it belongs to, that it should do some internal changes:

  Entry<MutableKey<String>, Value<SomeEntity>> entry = mutableHashMap.getEntryByKey("myKey");
  entry.setKey("myNewKey");
That logic could take an internal hash map, remove the element by the old key and add it with the new key. So, to an outside user it would seem like you can change the keys.

The only problem would be that depending on the language you're using, you wouldn't change the objects directly, but would use those containers and it would essentially just be some boilerplate around a regular hash map. For example, Java has MutableInt and similar classes, which here would be hooked up to the MutableHashMap that they belong to.

Then again, I can't come up with many cases where something like that would be nice to have, since if you want to "change" a key, you can just do the following manually:

  var ourValue = myHashMap.get("myKey");
  myHashMap.remove("myKey");
  myHashMap.put("myNewKey", ourValue);
the nitpicker in me wants to say that the hash key can change (and it works if you rehash items whose key changed), but lookup by key will fail because the item will landed in the bucket of its original hash... but yes keys can't change if you want your values to be retrievable by key.
Is it nitpicking if we end up with fewer bugs as a result of the conversation? :)
that's the spirit!
> someone who had done pretty well in our DS

> Him: “I can’t. I need to be able to get both the key and the value and hash tables don’t store the key”

How could he do well in the data structures class? This is the definition of a hash map or hashed dictionary, so this is basic knowledge of data structures that is taught in this class and central to know to even have a chance of passing the exam.

No, technically he's right. On paper, a hash map creates an index in an array-like structure from the key, but does not necessarily store the key in a retrievable way. The "Hash" in hashmap comes from the fact that the key is somehow hashed (an often irreversible procedure) to determine the memory location to store the value.

In practice it's not the case, but very technically from a purely theoretical standpoint, I think he's right.

EDIT: untrue on any finite sized array, due to collisions. See below, and sorry for the brain fart!

There's no theoretical way for a hash map to work without storing the key - the reason for that is hash collisions in presence of which you do need to run equality comparison with stored keys otherwise you would overwrite data just because of hash clashes.
>> In practice it's not the case, but very technically from a purely theoretical standpoint, I think he's right.

> There's no theoretical way for a hash map to work without storing the key - the reason for that is hash collisions in presence of which you do need to run equality comparison with stored keys otherwise you would overwrite data just because of hash clashes.

There's a ton of material in a Data Structures course. I'm sure the point about storing the key was mentioned at some point, but it's not the focus when talking about different hashing strategies etc. For people with a bunch of experience (e.g. I'd been writing Perl for years before this, so being able to iterate across a hash and get (k,v) pairs was obvious) it's a detail that is already there in your brain, but if the DS course is your first exposure to a hash map, it's a detail that can easily get lost in the huge forest of other brand new things to learn.

> but if the DS course is your first exposure to a hash map, it's a detail that can easily get lost in the huge forest of other brand new things to learn.

My experience differs: It is the common situation that the theory is taught in the lecture, and then each week you have to do quite some exercises to implement all the newly learned data structures in code (lots of work to do each week :-) ). So, if you forgot such a "detail", the code to write for next week simply won't work - 0 points.

This way, it is rather unlikely that you will forget such a "detail" in the forest of new things to learn. This statement in particular holds for students who had done pretty well in DS as the one you are talking about.

Not to date myself too much but the course was taught in Eiffel :). On top of the theory, and on top of the practical details, there was also the fun of learning an obscure quirky programming language you were unlikely to ever use again.

I loved it all and had a great time. Lots of people really did not.

> So, if you forgot such a “detail”…

Sure, very true in the short term. Next semester though? That code doesn’t matter and most people don’t have flawless long term memory.

Collision-free hashes exist. They are just not used on practice to build hash maps, but if you use a 128 bits hash with homogeneous distribution, handling collisions is irrelevant.

Besides, just because you are storing the keys, it doesn't mean it is viable to retrieve them. On the collision aware maps you see on CS, iterating through the keys is extremely inefficient.

The OP's description is clearly somebody that has learned the theory, but don't have any practical knowledge.

I never understood why a 'dictionary' (so called conveniently in python) is called a 'map' in c++ and yet, a 'hash' in ruby. On a side note, a map in ruby is an operation that actively maps one thing to another. So confusing. Finally reading what you just wrote makes the pieces of this puzzle to fall in place! Never had a data structures class.
According to https://stackoverflow.com/a/2884200 map and dictionary are just terms for the same data structure concept. On the other hand: there exist other backings for this data structure than hashing the key, such as binary trees (for example red-black trees or AVL trees).
The followup question is "Can you explain a strategy for resolving hash collisions?"
Depends on the use case, sometimes a list is more appropriate. On an old machine, Java 17 can iterate a list of 30 million strings looking for a match in around a half second. Just checked it in jshell. If the use case was that the map's keys could potentially change over the lifetime of the map or if the value's were not idempotent and if iterating 30 million items occurs fairly infrequently, then an ArrayList (in Java) might be the best choice.
FWIW, actually, one thing I learned in practice that’s wasn’t highlighted in my Algorithms course: overhead (constant C) matters. You can feel good about yourself for choosing an algorithm that scales in O(lg n) time, but if your you ignore the cost of each operation (C) you might be slow.

For example:

1. When n is small, an array is almost always better. Arrays have very little overhead compared to even a hash map.

2. Algorithms with the same O() may still have significant differences at runtime and might be balanced differently between insert and search times. AVL trees take longer than Red Black trees to insert, but might be 1 level better in height. That means one less access. Useful for a routing table, for example.

So, in summary, if your looking at other people’s code and see lots of arrays don’t get too smug…n is usually small.

Also cache matters a lot. If n is small an array is always faster by a big margin.
(comment deleted)
a good example of this is Fibonacci heaps. on paper they're great, but they result in egregious pointer chasing, while radix heaps are less flexible but can be backed by a contiguous array.

weirdly, in all my recent algorithm work, only the big-O has mattered (or it's all just NP-hard or even EXPTIME.)

And yet there are plenty of developers who happily loop through an array a couple of times looking for an object with a specific key. In Javascript.

Knowing the theory doesn't mean people apply it in practice.

I feel the same way. I hate interviewing because I usually need to study for stuff I won't use. I also didn't do CS in college and some times I feel like this is the missing point in my career.

Some companies have a more straight forward interview process. Try to stay away from big companies. There are startups paying very well.

Tech interview questions with leet code is the equivalent of standardized tests (SAT, ACT) for admissions to college/university. Neither are anything like what is required of you once you are accepted.

I'd take people that have initiative, want to learn and are coach-able over someone that can excel at taking tests.

You are a good programmer. Period.
For a recent interview I was asked to build an IOC dependency injection library in 2h and the task was made “deliberately” unclear according to the interviewer. So I spent 2 days researching IOC libraries, building some nice examples of how it should work to get a feel for the API, writing tests up front, writing the library and adding docs. Then I got an interview! Fantastic I thought, I passed the technical with my 100% tested IOC container that had a nice interface for injecting dependencies and even options for injecting singletons or new class instances with configurations passed into the constructor.

Now I went through with them some extra things in the interview and fixed some things about the code and handled some things a bit better. After this investment of time I was told I didn’t handle errors well enough in this 100% coverage tested example code of a library. This in my opinion was not true or even discussed in the interview, error handling was certainly not specifically mentioned in the assignment.

Anyway to address your point, I don’t think you should necessarily believe what other people say about you in job interviews; there are various types of interviewer but mostly the feedback is post rationalisation of “that’s not how I would have done it” even if your solution solves the problem perfectly. For this reason I’ve decided unless I can’t afford to feed myself I will avoid doing at home coding exercises that are deliberately vague in the future.

If you want to get better at in person/under pressure coding exercises I highly recommend taking on Advent of Code [1] one year, these are the opposite of the vague problem specified above as there is an exact and clear right answer to collect each star.

[1] https://adventofcode.com/

I start a new gig Monday… my best interviews were with two big tech companies… one hired me and the other said I lacked “code fluency”, which I had never heard of in those words.

Some of these places expect your first draft of a weird abstract problem to be perfectly readable in a live coding environment. Without any pressure my first draft is feeling out the problem and then trimming everything up.

In any case I landed at my preferred company, which is very exciting.

Similar experience last week

The company added a take home project into the interview process retroactively

Said the task would take 2-4 hours

It took me days of research and development

And then I re-did the project in a few hours, simulating github commits to a new repo so they could see the time it took

They graded unknown things

"Build a custom IoC for an interview"

Are you kidding me? The IoC research was probably good experience if you've never seen them before, but yeah you ran into the "easier to criticize than do".

I almost guarantee none of the people involved went through the same interview process where they had to code something for two days. This is how the hazing cycle begins, because everyone thinks "man I had it hard, and my hard experiences forged me, so I'll be really hard on the next round of people".

Dumb idea. That is a conscious thought bubbling up from subconscious "trauma" and humans for whatever reason replay / reinflict their repressed emotional damage on others. I believe this is because trauma makes you feel alone, and it makes a person feel less alone.

But anyway, so the organization hazes people, who then haze the next round even worse, who then haze the next round even more really bad worse.

This basically is what IT interviewing is after 20 years of collective downward spiral hazing.

The military generally has this figured out with basic training. Basic training is basically hazing to toughen up and desensitive normal humans into becoming soldiers. But the military seems to have a policy / training feedback loop that prevents the hazing from getting worse, and staying at the level of psychological impact that they get the desired result from.

Interview gauntlets have a desired result: filter out the chaff, get good candidates. As google itself shows, one of the progenitors (along with MIcrosoft) of the great interview hazing feedback loop, that it doesn't work. The end goal of "good employee/developer" isn't enhanced by the gauntlet/hazing. And yet everyone does worse and worse variants (look at Amazon: people hate working there, and the reputation of a horrible workplace IN IT, not just on the warehouse floor, is now ubiquitous in the industry).

Anyway, fuck our industry interviewing hazing. What a stupid bunch of apes we all are, interviewing in ostensibly a purely mathematical/technical domain has been reduced to a bunch of Lord of the Flies level dystopian human psychology.

Geez. Half our our candidates wouldn't even know what an DI libary is.
At a certain level we all should ditch companies for giving these monstrous coding challenges or they'll probably never learn. E.g. I think it's ridiculous to let people write code when applying to Senior Developer or even worse Software Architect positions. If you can't find out otherwise if the person is a fit or not you're doing it wrong.
For better or worse, when I was interviewing developers I would give specifically vague requirements, since requirement gathering is a skill that I think (senior) developers must have. I don't think that's a useful thing to do in a take-home assignment, though, since you can't clarify requirements with your client in that situation. That said, I admit that I would also expect error handling to be addressed in any piece of software written for any purpose.

Interviewing is a nightmare on both sides of the fence, though. There's a reason why it's a good idea to build up and leverage your network of coworkers.

The code had tests checking if errors threw under certain conditions... like I say it had error handling but we changed the way it worked during the interview so we needed to add some extra error conditions which we did and test coverage remained 100% so all paths in the code were tested.
> when I was interviewing developers I would give specifically vague requirements

I did this for a while and realized that it typically panicked the people we were interviewing, especially if they were on the junior/mid side of things and as a result, gave lower-quality answers.

> I would also expect error handling to be addressed in any piece of software written for any purpose

I guess it depends on what people are hiring for but in the long list of things I need out of that person, this ends up lower on the list

>That said, I admit that I would also expect error handling to be addressed in any piece of software written for any purpose.

I always view assignments and live coding in interviews as a startup that has runway of an hour or two. Would error handling help this startup survive another day? No. But properly covering the main use case - may in fact be.

It's fair to want the candidate to mention the edge cases and tests for it in the end verbally, there I agree. But expecting 120% performance giving out vaguely formulated problems with extreme time constraints and the pressure of an interview to me seems almost delusional.

This reminded me about obe interview I had a year ago related to environments management in IaC.

The Senior Architect that interviewed me asked a question about correct infrastructure state management giving as an example their current infrastructure, giving me a hint that number of environments will grow expenentionally.

Ive shortly explained to him that the architecture they chose will be really hard to maintain when the numbers of environments grow past single digit numbers and a better approach would be to store the state per part of environment.

He got really mad at me for pointing that out (on the meeting were also other ppl) and tried to force me to chose the same approach as he did. I refused and proposed IMHO a better solution.

Long story short - did not get this job. So yes, sometimes ppl will dump you because you are overqualified and not only underqualified.

Happens more often that you might think. Score high on tech, but very low on diplomacy / political awareness. Managers want staff to make them look good -- at all cost.
(comment deleted)
(comment deleted)
Good to know. I have pretty high opinion of myself too.
lol just want to add that KISS stands for 'Keep it simple, stupid'
That's also how I learned it, but I prefer the way OP wrote it. I think it's nice.
I don't know if you're a good or bad programmer, but I'll tell you this about job interviews:

I've given dozens of interviews over the past 3 years. I'm fairly certain everyone got out of the interview with me feeling like they did very poorly, when in fact a lot of people were doing well. All of the people I ended up hiring told me "I was sure I completely failed your interview".

You don't know what interviewers are looking for, so don't make assumptions. I'm almost never looking for a "correct" answer. I'm always looking for your behavior and attitude when answering those questions. My definition of a good programmer is someone who understands that it's a team sports, who values clear communication and who knows how to read the doc on their own. You may or may not have implemented your own lisp in your spare time, but this is secondary.

If you ask me to review the quality of your code, I'll spend more time reading your commit messages and variable names, than you realize. It's as important as the choice of algorithm and data structure.

Other interviewers value other things. There's no one thing.

TLDR: You don't know how well you did in interviews, it's very likely you're better than you think.

> All of this together allowed me to build and sell already two startups. Develop and maintain easily many web sites and SaaS which creates me nice passive income

A successful entrepreneur, perhaps, but not necessarily a good programmer.

There's really nothing wrong with being dead average. The interview process is backwards in this industry anyway. No need to worry. It sounds like you're doing fine.

I went on an interview some years ago and was asked how I'd architect a certain situation with Models and Controllers. I spent some time discussing why that wasn't the right solution for what they were trying to do, and they said thanks but no thanks.

Now to be fair to them, I was asked to do a certain task and I failed to do that task. It's pretty cut and dry.

But I also walked away glad they turned me down, because if they're going to try and force me to do something a specific way when that way is inefficient, or troublesome or just plain not the best answer, then I wouldn't really want to be working there anyway.

> Now to be fair to them, I was asked to do a certain task and I failed to do that task. It's pretty cut and dry.

Being that cut and dry (read: binary) is a problem of its own; and it's probably the more important one to solve.

I've handled interviews like this before by saying "normally I wouldn't use Models and Controllers for this task because X, but since you asked, I assume you just want me to demonstrate that I know what Models and Controllers are, and that's what I'll do".

How they react to that is telling. I've had interviews where they say "great point, that's exactly the kind of thinking we need!" and other interviews where they take it as a challenge to their authority. The latter is of course a red flag and you should excuse yourself from any further interviews.

Reading through your post, I am noticing some trivial English mistakes that are common to non-native speakers.

It's worth knowing that while you have successfully articulated everything, some people will still see your mistakes as red flags for future communication. Some might even assume that you will be making trivial code mistakes, too; despite there being no evidence of that.

That kind of prejudice is common, and difficult to confront.

There is no real need for you to improve your English skills: your writing isn't ambiguous or missing anything. Even so, it's worth recognizing the social dynamic that is likely to happen, and how that affects you.

That is true. I am not a native English speaker. I should work on my English skill though.
In a moral sense, you shouldn't need to. Your English is functional enough to work with. It's not your fault if people make poor judgements about your ability based on your English skills.

Unfortunately, we can't expect all the people we work with to overcome their prejudices, so it's probably still useful for you to improve your English skills.