To join a WhatsApp group with a link, tap the link, check the group name and picture on the preview screen, then tap Join group. That is the whole job, on Android and on iPhone alike.
The part worth slowing down for is the check. A link tells you nothing about who is inside or what they post, and anyone can give a group any name they like.
How to join WhatsApp group with link on Android and iPhone
Group invite links start with chat.whatsapp.com/ followed by a long code. You can get one from a friend, from a post, or from a directory page. The steps are the same wherever it came from.
If the link is plain text and not tappable, copy it into Chrome or Safari and the same page opens. Links that arrive inside Instagram or another app's built-in browser sometimes refuse to hand over to WhatsApp, and opening them in your normal browser fixes that. The full list of reasons a link fails is in our troubleshooting piece on a link that will not open, and the official wording lives in WhatsApp's help centre.
Reading a link before you tap it
A genuine group link has a fixed shape: the address is exactly chat.whatsapp.com, then a slash, then a code made of letters and numbers. The part before the first slash is the part to read. Lookalikes change a letter, add a hyphen, or use a different ending, and they are built to be skimmed past on a small screen.
A short link from a link shortener hides all of this, so open it only if the person who sent it is someone you trust.
On a computer, or with WhatsApp Business
You can join from a laptop too. Open the link in your browser and the invite page offers to open WhatsApp on the computer or use WhatsApp Web. On most setups the group then appears in your chat list on your phone as well.
The WhatsApp Business app joins groups through links in the same way as the normal app. The steps do not change.
What to check before you tap Join
The preview is thin. You get a name and a picture, and that is all, so the checking happens in your head.
Joining without the admin saying yes
You do not need an admin to add you. The link itself is the permission, which is why people post them publicly. The one exception is a group with join approval turned on, where an admin has to accept your request first.
You also do not need to be saved in the admin's contacts. The admin may never notice you arrived.
Assume that every member of the group can see your phone number once you are in. That is the real cost of joining a large public group, and it is the reason to be choosy about which ones you join from a link a stranger gave you.
Group links and channel links look different
Group links begin with chat.whatsapp.com. Channel links begin with whatsapp.com/channel, and a channel is a different animal: only the admins post, and you follow it rather than join it. WhatsApp's announcement of channels explains the idea. If your link is the second kind, you will see a Follow button where a group would show Join group, and nothing in this guide about member numbers applies.
After you are in
Mute the group first. A busy group can send a flood of messages before you have decided whether you like it, and you can unmute later.
Then tap the group name at the top and read the description. Good admins put the rules there. If the group is not what the link promised, leave. WhatsApp posts a small notice that you left, which is mildly awkward and entirely harmless.
Never type a one-time password, a UPI PIN or a card number into a group, and ignore anyone who offers to "verify" you through a separate link. Real groups do not need any of that.
A last point on manners, since a group is a room full of people you have not met. Read the pinned message or description before you write anything. Introduce yourself only if the group does that, and do not message members privately because you saw their number. Most admins remove people for that faster than for anything else.
Where to start looking
If you do not have a link yet, browse the WhatsApp group links directory by category and read the group names with the same suspicion you would bring to any link from a stranger. For the bigger picture of how invite links work across apps, our guide to finding, joining and vetting online communities is the place to go next.