informal word or expression for "In Fact"
I have heard "In Fact" it too formal. What do you propose to use instead In Fact in informal conversations?

Question

Answer

Try "actually."

Answer

'In fact' isn't especially formal : we use it all the time in normal speech.
But - as Brad C suggested - the word 'actually' is very good alternative.

Answer

This is where I would suggest you consult your local thesaurus...

But try the following:

Truth be told
indeed
truly
really
literally
as a matter of fact
in reality

or any of these that I got from a thesaurus (context dependent but words that might help you)...

adv. without a doubt

absolutely
    actually
    admittedly
    as a matter of fact
    assuredly
    authentically
    beyond doubt

categorically
    certainly
    de facto
    easily
    for real
    genuinely
    honestly

in actuality
    in effect
    in fact
    in point of fact
    in reality
    indeed
    indubitably

legitimately
    literally
    no ifs ands or buts
    nothing else but
    of course
    positively
    precisely

surely
    truly
    undoubtedly
    unmistakably
    unquestionably
    verily
    well

Nick

Answer

"Too formal" is   a popular mythology,  associated with "dumbing down".

There is no such thing as a "too formal".

You can substitute   a term  like  "objectively" for "in fact".