Nicodemus came to Jesus by night

[tonychanyt]

John the Baptizer had a public run-in with the Pharisees (John 1:24, Matthew 3:7).

When Jesus publicly cleansed the temple, the temple authority confronted him (John 2:18).

John 3:

1 Now there was a man of the Pharisees named Nicodemus, a ruler of the Jews.

Nicodemus was a member of the Sanhedrin.

2 This man came to Jesus by night and said to him, “Rabbi, we know that you are a teacher come from God, for no one can do these signs that you do unless God is with him.”

Nicodemus respected Jesus, calling him "Rabbi".

Why did Nicodemus come to Jesus by night?

The Bible does not explicitly say why. I can only guess. By this time, there was increasing opposition and hostility towards Jesus among the religious leaders. However, Nicodemus did not share the same opinion as his colleagues. Though he was a member of the religious ruling council, it was not an official visit. He wanted to talk to Jesus privately to find out more about him. He came under the cover of darkness to avoid the daylight publicity. He just wanted a private conversation with Jesus without the crowd.

See also What happened to Nicodemus?