WhatsApp is a fantastic service for letting you chat with and send picture- or video messages to your contacts for free over a data connection without using up your tariff allowances. Now it's possible to send documents for free, too. Here's how to share PDFs on WhatsApp. Also see: How to make video calls and group video calls on WhatsApp.

The new Documents feature is rapidly rolling out to WhatsApp users around the globe. It doesn't seem to matter which version of the app you are using in order to see the new feature, but if the contact you want to send a document to has not updated their app then they won't be able to receive it. It's a good idea to keep your apps up to date in any case, since you'll benefit from new features and bug fixes.

You can update WhatsApp on an Android phone by launching Google Play and clicking the three horizontal lines icon at the top left of the page, then choosing My apps & games and checking to see whether a WhatsApp update is available. If it is, tap on the app to launch it, then tap Update and accept any new permissions. Also see: How to avoid WhatsApp scams, viruses and hoaxes.

On an iPhone you should launch the App Store and select the Updates tab at the bottom right, then look for an update to WhatsApp and tap Update.

On both platforms you can configure automatic updates, but it's worth checking in the relevant app store as to whether these occur only over Wi-Fi. This is the best choice is you have a limited mobile data plan, but if you don't ever connect to Wi-Fi it's easy to forget to check whether app updates are available. Also see: How to use WhatsApp on the Web.

How to send documents on WhatsApp

• Launch WhatsApp and tap on an ongoing conversation in the Chats tab to open an existing thread, or tap on a contact in the Contacts tab to start a new conversation.

• Tap the paperclip icon at the top right of the screen to add an attachment to your message.

Send document on WhatsApp

• You'll see six icons pop up. If you are able to send documents over WhatsApp then the first icon will be 'Document'. If the change hasn't yet rolled out to you then you'll see a Gallery icon. (The update sees WhatsApp roll Photo and Video into a single Gallery icon. If you want to send either of these types of media, you simply choose Gallery and select your content on either the Photos or Videos tab.)

• Tap the Document icon. If your contact hasn't updated their WhatsApp app, a message will pop up telling you as much. If they are running an up-to-date version of the app WhatsApp will bring up a list of documents stored on your phone, but for now it supports only PDF files.

Send document on WhatsApp

• Select a PDF by tapping on it. To send press Send in the pop-up window.

Read next: How to read a WhatsApp message without the sender knowing | WhatsApp ban: What you should know | How to restore WhatsApp on a new phone

Follow Marie Brewis on Twitter