According to a report by Yomi Kazeem for Quartz, these knock-off versions are not available on the app store. People download these “mods” from unofficial sources, or share them offline from device to device. [Read: Spotify’s new iOS design makes it easier to navigate] Kazeem noted that these alternative versions, such as GBWhatsApp and YoWhatsApp, are even more popular than Facebook and Messenger. They offer additional features including a password lock for selected conversations, a massive library of themes, a custom status message for specific contacts, and file previews. Naturally, with these unofficial versions, there’s a security risk of these apps being prone to malware. More importantly, chats in these mods are not encrypted, so a hacker or a government could potentially eavesdrop on your conversations. Plus, there’s a chance that WhatsApp may ban them, as they violate the company’s terms and services. Modified versions of popular chat apps aren’t uncommon. Telegram has plenty of unofficial clients such as Plus Messenger and Supergram. The company often puts out advisories against using these versions as they might be harmful to your privacy and security. Kazeem’s piece is a compelling look at the black market of WhatsApp mods and their creators’ ingenuity. You can read it here.