How extensible is opencart ?

(I am new to opencart) I recently started working on a website that was built with opencart 2.3.x
The website has been working good for us till now. We are at a stage where we want to take the development to the next level and hire couple of people in house to improve the website and the experience. I have some concerns about opencart and would like to know expert's opinion:

- Is open cart extensible enough for a large scale business?
- Can we make changes to the default code base of opencart comfortably (i.e. without worrying about breaking other things)
- Can we create an API and use that to drive the Single page app front-end built with react?
- Can we easily scale in infrastructure and database easily?

The question that I primarily want to answer is, should I continue investing my time and effort in opencart or switch to a any other launguage or framwork that will provide me the flexibility to take my business to the next level of e-commerce marketplace?

- Is open cart extensible enough for a large scale business?
Yes, it basically works well up to a million+ of products, if professionally installed
and peaked by a Pro, in a professionally built high speed Server Environment.

- Can we make changes to the default code base of opencart comfortably (i.e. without worrying about breaking other things)
Not really, OC is a multi-multi-multi MVC(L) Framework Software, and not a single
Page HTML Construction. And it's all done by Variables, to be declared/defined
throughout the different 'Sections', (plus eventually the DB!) to make something work
somewhere on a Page.

- Can we create an API and use that to drive the Single page app front-end built with react?
Probably not, but I don't know REACT. (porssibly by Use of an OC v.3.x Version ... )

- Can we easily scale in infrastructure and database easily?
Depends on, what easily means to you. For an OC Insider, it might be
easy, but for Fellows like me, even 4.x Years after, it's hard work and testing.
---
For a Pro OC Coder, it's no Problem, to enhance Opencart, but for anyone else,
it could end up as a Nightmare. I would therefore recommend, to rather get one
of the well-known Professionals, instead of depending on 'internal Sources',
or it could end up as a (time-wise) very expensive Adventure, and no working
Shop at all.
Good Luck!
Ernie

Thanks for your suggestions and insights.

It seems opencart is extensible and can be extended to implement complex logic.
We will be able to make changes but will just have to find an expert programmer.

What do you think about ocMod capability. I am on the fence with it.
It does provide plug and play behavior and is very powerful, but on the other hand, it makes making native OC code changes difficult.
I am assuming that ocMod are created considering the webiste is running un-modified version of OC code base. If we update the native code the Mod may misbehave or just not work. Is that correct?

Well, it's not that complicated, when it comes to OcMod (or VqMod), just compare
it with a Door-Key, it either matches, or then not, i.E., if one changed some so-called
'anchors/tags' in the OC Source, and so disabling an OcMod/VqMod from finding
it's 'LINK', to do it's job somewhere, kind of. But for someone, familiar with, how this
'override' Function works, it's not a problem, to do all kinds of things.

It might get a little more complicated, if one uses a large amount of such extensions,
like me, using up to 100+ of such Mod's, since some of them possibly already changed
existing default anchor/tag Values, hindering a new extension from finding it's links/anchors,
to do it's own job.

And by use of OcMod, one could basically install a range of such extensions, and then
'replace' the OcModded 'cached' files with the OC DEFAULT Files, to so have all those
Extensions built-in into the 'default' OC Core, and it's way of doing things.

In a professional (enhanced) installation, this would be the most perfect way of building
a shop, but only, if everything has been tested and all extensions have been installed and
work well. It only depends on the capability of a Coder, then, there are no limits. And one
needs to be aware of, that, by use of another Theme, or other Modules, one needs to recall,
was has been done before, in order to possibly make something New to work again.

But one should better NOT use OcMod and VqMod in the same Installation, so, better
rewrite OcMod's to VqMods, or in reverse, to so only use one kind of Override Engine in an
installation, since it's of no use, to have two different ways of basically doing the same thing.

And don't worry about 'upgrading' OC Versions, since there are no UPGRADES, but complete
new Versions, usually containing a lot of completely new Code. It therefore does not matter,
if one changes existing Source, since everything will be new in later Versions anyway.

Just to give you some basic Ideas on this !
Good Luck!
Ernie