Learn German: Die Journalistin schreibt, die neue Software werde perfekt funktionieren. - The journalist writes the new software will function perfectly.

Werde is the Konjunktiv I (Subjunctive I) form of werden for the third-person singular (die Software). Because this is reported speech, we use Konjunktiv I to show we are merely conveying the journalist's claim. If it were a direct, guaranteed fact, you would use the regular indicative form wird.

Why is there no dass (that) connecting the two halves of the sentence?

In German reported speech, you can leave out the conjunction dass. When you drop it, the reported clause takes standard main-clause word order, meaning the conjugated verb (werde) sits in the second position. If you included dass, the conjugated verb would be kicked to the very end: ... dass die neue Software perfekt funktionieren werde.

Both the future tense and the passive voice use werden. How can I instantly tell which one this is?

Look at the second verb at the end of the sentence. If it is an infinitive (like funktionieren here), the sentence is in the future tense. If it is a past participle (like repariert or gebaut), the sentence is in the passive voice.

What if the sentence was about plural "new programs" instead of singular software? Would we use werden?