Adjective endings after 'viele'
I want to say in German 'and has many interesting books'

but cannot find out definitively what an adjective ending would be after 'viele'?

The only adjective ending charts I can find list adjective endings for either definite or indefinite articles. As it is a plural cannot obviously use the definite article and hence I'm assuming would class 'viele' as an indefinite article and the sentence would be

'und hat viele interessanteN Bücher'

however numerous translation websites translate the sentence as

'und hat viele interessantE Bücher'

I know these are not perfect translators and shouldn't be relied upon but would obviously like to clarify what the correct adjective ending should be?

Vielen Dank

Question

Adjective endings after 'viele'
I want to say in German 'and has many interesting books' 

but cannot find out definitively what an adjective ending would be after 'viele'?  

The only adjective ending charts I can find list adjective endings for either definite or indefinite articles. As it is a plural cannot obviously use the definite article and hence I'm assuming would class 'viele' as an indefinite article and the sentence would be 

'und hat viele interessanteN Bücher'

however numerous translation websites translate the sentence as  

'und hat viele interessantE Bücher'

I know these are not perfect translators and shouldn't be relied upon but would obviously like to clarify what the correct adjective ending should be?

Vielen Dank

Answer

Viele interessantE Bücher.
Answer is simple. It's about declension.

1. Nominativ (Wer oder was?)
2. Genitiv (Wessen?)
3. Dativ (Wem?)
4. Akkusativ (Wen oder was?)

So "...und hat viele interessante Bücher" in this case is the Akkusativobjekt. 
...und hat wen oder was? Viele interessante Bücher.

So that's the simplest form. Using "viele" always leads to a simple "e".
Viele interessantE Bücher.
Viele interessantE Frauen.
Viele interessantE Kinder.
Viele interessantE Äpfel.

So whenever this looks different, it's another case. Not the Akkusativobjekt anymore. For instance:

Ich gebe vieleN interessanteN Menschen einen Kuchen.
Which case? Dativobjekt - Ich gebe wem einen Kuchen? VieleN interessanteN Menschen.

So you see that you should study more about the German declension to clear up your confusion. 
Hope it helps.

Answer

It's called the "strong" declension of adjectives. It is the same as if there were no article.
interessante Bücher - viele interessante Bücher
Das Lesen interessanter Bücher - Das Lesen vieler interessanter Bücher

Hope that helps.