Контактный центр указан тут, в приложении.

Указан is the short passive participle of указать (to indicate / point out / specify / list).

In sentences like this, a short passive participle works like the predicate:

• центр указан = the center is indicated / listed

This structure is very common in written, formal, or informational Russian.

Compare:

• указать = to indicate
• указан = indicated / listed / specified

So the sentence is built around the idea the contact center is listed/shown here.

Because указан must agree with центр.

Центр is:

• masculine
• singular
• nominative

So the short participle also has to be masculine singular:

• центр указан
• компания указана
• место указано
• данные указаны

So here:

• контактный центр = masculine singular
• therefore указан

It is in the nominative case.

That is because in this kind of passive-style sentence, the thing being described is in the nominative:

• Контактный центр указан...
  = The contact center is listed...

Even though English might make you think of something like an object, in Russian this phrase is the grammatical subject-like element of the sentence.

So:

• контактный = nominative masculine singular adjective
• центр = nominative masculine singular noun

Russian usually does not use a present-tense form of to be in sentences like this.

So English:

• The contact center is listed here

becomes Russian:

• Контактный центр указан тут

There is no separate present-tense is.

If you wanted past or future, then Russian would use forms of быть:

• Контактный центр был указан... = was listed...
• Контактный центр будет указан... = will be listed...

Because в приложении clarifies what тут means.

• тут = here
• в приложении = in the app

So the sentence is basically:

• here — in the app

The second part narrows down or explains the first part. In English we often do the same:

• here, in the app

That is why the comma appears: в приложении is an уточнение, a clarification.

Yes, but only slightly.

Both mean here.

Very roughly:

• тут is often a bit more conversational or immediate
• здесь is a bit more neutral

In many everyday sentences, they are interchangeable:

• Контактный центр указан тут
• Контактный центр указан здесь

Both are understandable. The choice is mostly about style and tone, not a big grammatical difference.

В приложении uses the preposition в + prepositional case to mean in the app.

Base form:

• приложение = app / application / attachment

Prepositional singular:

• в приложении

So:

• в = in
• приложении = prepositional singular of приложение

Important note: приложение can mean both:

• app / application
• attachment / appendix

Context tells you which one is meant. In your sentence, it most likely means the app.

In this sentence, yes, the comma makes sense because в приложении is a clarification of тут:

• тут, в приложении

It works like:

• here, in the app

If you removed тут, then no comma would be needed:

• Контактный центр указан в приложении.

That is a straightforward statement: The contact center is listed in the app.

So the comma is connected to the extra clarifying structure, not to в приложении by itself.

Yes. Russian word order is flexible, and changing it changes the emphasis more than the core meaning.

For example:

• Контактный центр указан тут, в приложении.
• Тут, в приложении, указан контактный центр.
• В приложении указан контактный центр.

All of these are possible, but they highlight different parts.

In your original sentence, контактный центр comes first, so the sentence starts with the thing being talked about. Then тут, в приложении gives the location.

That word order is natural if the topic is already the contact center, and the new information is where it is listed.

Yes, somewhat.

Указан is very common in:

• instructions
• interfaces
• official writing
• informational text
• customer support language

It sounds more formal or administrative than a very casual verb.

Depending on context, Russian might also use other verbs such as:

• есть in very simple speech
• находится
• показан
• приведён

But указан is perfectly normal when something is being officially or clearly specified somewhere.

So for app text, support text, or interface language, it fits well.