If you truly need WhatsApp to function on iOS 7.1.2, jailbreaking (using Pangu7 or EtasonJB) allows you to install WhatsApp Legacy Patch from Cydia (repo: repo.hackyouriphone.org). This tweak tricks WhatsApp’s servers into thinking you are running iOS 9.
Pros: Restores voice calling and status viewing. Cons: Security risk; battery drain; bannable by WhatsApp (Meta). whatsapp old version for ios 712 download upd
Since Apple revoked most free developer certificates, you now need a paid Apple Developer account ($99/year) to sideload on iOS 7. Otherwise, the app crashes immediately after 7 days. If you truly need WhatsApp to function on iOS 7
For iOS 7.1.2, the Pangu7 jailbreak is untethered (works after reboot). Once jailbroken: Recommendation: Use WhatsApp Web via Safari on iOS 7
Avoid downloading .ipa files from untrusted sites. Prefer official App Store re-download, device backup restoration, or upgrading hardware/OS. If continued use of an old client is essential, understand the security and service-availability risks and consider isolating the older device from sensitive accounts and data.
Do not use an old version of WhatsApp for sensitive communication.
Recommendation: Use WhatsApp Web via Safari on iOS 7.1.2 instead. Navigate to web.whatsapp.com in Safari. While you cannot get push notifications, you can read/write messages via the web interface without installing any IPA.