We know that someone named John (1:1, 4, 9) wrote the Revelation. The author is in exile, but we do not know whether this is self-imposed or due to some kind of official decree. The reason for his exile is clear, it is because of the Lord. However, it should be noted that the present location of the author, i.e., at the time of writing, is unknown. Rev 1:9 suggests that John had his vision on the island of Patmos, but it does not suggest that John is still there, nor does it suggest that John wrote Revelation while he was there.
Thus, John may have taken much time to pray, meditate and think through his visionary experiences and how best to communicate those to the communities that he served. Thus we should be careful in allowing presuppositions and assumptions to guide our understanding of how this text was put together and when and how it was written.
Some scholars have suggested that some sections of Revelation may have been written and used much earlier, and thus within Revelation there are both early and later materials. Although, I must admit to a certain scepticism regarding our ability to discern various layers of tradition and then date them. Such proposals and conclusions seem more to be driven by circular reasoning.
Rev. 22:6-7 suggest that he was a prophet, perhaps part of a prophetic group. Presumably he was well known to the audience as he does not explain to them who he is. He writes to the Churches with some authority, which may suggest an ongoing relationship with them.
John must normally have been active as a prophet in the churches to which he writes. The seven messages to the churches reveal detailed knowledge of each local situation, and 2:21 presumably refers to an earlier prophetic oracle of his, addressed to the prophetess he calls Jezebel at Thyatira. John was no stranger to these churches but had exercised a prophetic ministry in them and knew them well. (Bauckham, The Theology of the Book of Revelation)
The amount of specific information that the writer has not only about these specific churches, but also about the specific areas within which these churches are found suggests an intimate knowledge of these areas.
Traditionally the author is seen as the apostle, the son of Zebedee (Matt 10:2). Justin Martyr, calls him “John the Apostle.”
There was a certain man with us whose name was John, one of the apostles of Christ, who prophesied by a revelation that was made to him, that those who believe in our Christ would dwell a thousand years in Jerusalem; and that thereafter the general, and in short, the eternal resurrection and judgment of all men would likewise take place.
While, Irenaeus merely notes that “John wrote the apocalypse at the end of the reign of Domitian,” which suggests a dating of around 95CE. Many, if not most, scholars suggest that a dating to the reign of Domitian, is accurate. Eusebius suggests that John went to Patmos during the reign of Domitian, and then later returned to Asia minor to continue his work.
John does not appear to be a pseudepigraphic writing, that is, a writing written under the name of someone else in whose authority one wished to write or communicate. John makes no special claims about himself, and very little is communicated about the situation within which he wrote. The writer is simply described as a slave of God, and a brother to those whom he writes.
Scholars have suggested that the author of this work has a distinctively Jewish background, given the numerous allusions and echoes to the Hebrew scriptures and various Jewish traditions. In fact, the genre of apocalypse appears to be most at home within a Jewish worldview.