Čim nešto saznam, javit ću ti se porukom.

In this sentence, čim means as soon as.

So:

• Čim nešto saznam = As soon as I find out something

Compared with kad:

• kad usually means when
• čim is more immediate: it emphasizes that one thing happens right after another

So Čim nešto saznam, javit ću ti se porukom suggests:

• first I find something out
• immediately after that, I will contact you

In everyday speech, čim is very common for this kind of idea.

Because saznam is from the perfective verb saznati.

Croatian often uses a perfective present form after words like čim, kad, ako, and similar conjunctions when talking about a future completed action.

Here the idea is not:

• I am finding out

but rather:

• once I find out
• as soon as I come to know

That is why saznam is used.

Compare:

• saznati = to find out, to come to know (perfective)
• saznavati / saznavam = to be finding out repeatedly or gradually (imperfective, much less suitable here)

So Čim nešto saznam... literally looks like a present tense form, but in meaning it refers to a future event: as soon as I find out.

This is a very common feature in Croatian.

After certain conjunctions and time expressions, Croatian often uses the present tense to talk about future events, especially in subordinate clauses.

So in English you say:

• As soon as I find out, I’ll text you

Croatian does something very similar structurally:

• Čim nešto saznam, javit ću ti se porukom.

Even though saznam is formally present tense, the whole clause clearly refers to the future because the main clause is future:

• javit ću ti se = I will contact you

This is normal Croatian, not a mistake.

Nešto means something.

In this sentence:

• Čim nešto saznam = As soon as I find out something

In natural English, you might more often say:

• As soon as I find out anything
• As soon as I learn more
• As soon as I know something

But in Croatian, nešto works very naturally here and often has the sense of some information / anything definite.

Because Croatian future tense with ću is often written as:

• infinitive stem + clitic form of htjeti

Here the verb is javiti se.

In future tense:

• ja ću se javiti
• or more commonly in this word order: javit ću se

When the auxiliary comes after the verb, the final -i of the infinitive is dropped in writing:

• javiti + ću → javit ću

So:

• javit ću = I will contact / I will get in touch

This is standard spelling.

Javiti se is a very common reflexive verb meaning:

• to get in touch
• to contact someone
• to let someone know
• sometimes to check in or to call/message

So:

• javit ću se = I’ll get in touch / I’ll contact
• javit ću ti se = I’ll get in touch with you / I’ll let you know

The ti is the dative pronoun meaning to you.

This is a very common expression in Croatian. It does not necessarily mean a phone call only; it can mean contacting someone by any method unless the sentence specifies how.

Because the verb is javiti se, not just javiti.

This is one of those Croatian verbs whose meaning changes depending on whether it is reflexive.

• javiti can mean to announce, to report, to inform
• javiti se means to contact, to check in, to make oneself heard from

In this sentence, the speaker means:

• I’ll contact you
• I’ll message you

So the reflexive se is required.

It does not literally mean that the person is doing something to themselves in the English sense. In many Croatian verbs, se is simply part of the standard verb form and meaning.

Ti is the unstressed dative form meaning to you.

So:

• javit ću ti se = I’ll get in touch with you
• literally something like I will make myself known to you

Croatian often uses the dative pronoun with verbs of giving, saying, showing, and contacting.

Compare:

• Dat ću ti knjigu. = I’ll give you the book.
• Reći ću ti. = I’ll tell you.
• Javit ću ti se. = I’ll contact you.

Porukom is the instrumental singular of poruka meaning message.

So:

• poruka = message
• porukom = by message / via a message

The instrumental case is often used to show the means or method by which something is done.

Here it tells you how the speaker will contact the other person:

• javit ću ti se porukom = I’ll message you / I’ll get in touch by message

So this instrumental is similar in meaning to:

• by text
• via message

Yes, very naturally.

Even though the Croatian wording is literally closer to:

• I’ll contact you by message

in normal English the most natural translation is often:

• As soon as I find out something, I’ll text you.

Depending on context, it could also be:

• As soon as I know something, I’ll message you.
• As soon as I hear anything, I’ll let you know by message.

So porukom strongly suggests text/message contact, and I’ll text you is often the best idiomatic translation.

Croatian word order is flexible, but this order is very natural.

The sentence is arranged like this:

• Čim nešto saznam = time clause
• javit ću ti se porukom = main clause

Within the main clause:

• javit ću = future verb
• ti = to you
• se = reflexive particle
• porukom = by message

Other word orders are possible, but they may sound more marked or emphasize different parts:

• Čim nešto saznam, porukom ću ti se javiti.
• Čim nešto saznam, javit ću se ti porukom. → not correct
• Čim nešto saznam, javit ću se porukom. → possible if ti is omitted

Clitic placement matters: ću, ti, se are clitics, so they tend to cluster in specific positions. The original sentence sounds very normal and neutral.

Yes, depending on context.

The verb saznati basically means:

• to find out
• to learn
• to come to know

In real-life English, people often translate it flexibly:

• As soon as I find out something
• As soon as I hear something
• As soon as I know more

If the context is waiting for news, results, or information, as soon as I hear something can be a very natural English rendering.

It is generally neutral to informal, and very natural in everyday speech.

It is not slang, and it is not rude. You could use it with:

• a friend
• a family member
• a colleague, if the relationship is not too formal

The pronoun ti shows that the speaker is addressing someone with informal you.

If you wanted to make it formal, you would use Vam instead:

• Čim nešto saznam, javit ću Vam se porukom.

That means:

• As soon as I find out something, I’ll message you
  with formal you.

No, that would not be correct here.

After čim, Croatian normally uses the present form, not the future tense, for this kind of future time clause.

So the correct form is:

• Čim nešto saznam...

not:

• Čim nešto ću saznati...

This is similar to how English says:

• As soon as I know, I’ll tell you

not usually:

• As soon as I will know, I’ll tell you

So Croatian and English are quite similar in this respect.

Yes, absolutely.

You could say:

• Čim saznam, javit ću ti se porukom.

That means roughly:

• As soon as I find out, I’ll message you.

Adding nešto makes it slightly more explicit:

• as soon as I find out something / anything

Both versions are natural. Which one sounds better depends on context.

The main verb expression is javiti se.

Its dictionary form is:

• javiti se

Important related forms are:

• javim se = I get in touch / I contact
• javio sam se = I got in touch
• javit ću se = I will get in touch

Because it is reflexive, you should learn it together with se, not just as javiti.