Is trolling haram in Islam?

Yes, trolling is haram in Islam when it means provoking, mocking, or hurting people online. Deliberately upsetting others, insulting them, or spreading lies for a reaction goes against clear Islamic teachings about speech. Light, friendly joking that everyone enjoys is a different thing and is allowed.

What trolling usually involves

Trolling is posting things to annoy, humiliate, or start a fight. It often includes mocking someone's looks or beliefs, name-calling, fake claims, and pile-ons. The Quran forbids exactly these behaviours:

يَـٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوا۟ لَا يَسْخَرْ قَوْمٌ مِّن قَوْمٍ عَسَىٰٓ أَن يَكُونُوا۟ خَيْرًا مِّنْهُمْ "O you who have believed, let not a people ridicule [another] people; perhaps they may be better than them..." Quran 49:11

The same verse goes on to forbid insulting one another and calling each other by offensive nicknames, which is basically a description of a comment section on a bad day.

A Muslim's tongue should be safe

The Prophet ﷺ said: "A Muslim is the one from whose tongue and hand the Muslims are safe" (Sahih al-Bukhari 10). Typing is the tongue of the internet. He ﷺ also said that a believer is not someone who taunts, curses, or speaks obscenely (Jami' at-Tirmidhi 1977). Anonymity doesn't change this; Allah sees every account. See Can I use an anonymous account online as a Muslim?

What about trolling non-Muslims or "bad people"?

Good manners in Islam aren't only for Muslims. Mocking people of other faiths or insulting their beliefs to get a reaction is discouraged, and it usually pushes people further from Islam. Even when people attack Islam, the advice is to respond calmly or walk away. See What should I do when people insult Islam in the comments?

Jokes, memes, and banter

Islam doesn't ban humour. The Prophet ﷺ joked with his Companions, but his jokes were true and didn't hurt anyone. Friendly banter between friends who both find it funny is fine. It turns into trolling when the goal is to embarrass, deceive, or hurt. See Is it haram to tell jokes?

If you've trolled before

Many people did this before Islam, or as teenagers. Delete what you can, apologise where possible, and repent sincerely. Then use the same wit for good: kind replies, helpful posts, and humour that doesn't wound.

Key points

Trolling to mock, provoke, or hurt people is haram.
The Quran forbids ridicule, insults, and offensive nicknames.
Anonymous accounts are still accountable before Allah.
Harmless, honest jokes between friends are allowed.

Tip: Before posting a reply, ask: "Would I say this to their face, in front of my mum?" If not, close the app and come back later.