WhatsApp can&#x27;t tell me how many users were talking about <i>Peanut Butter Sandwiches</i> 30 seconds ago. WhatsApp can&#x27;t alert me when people suddenly start talking about earthquakes, super bowls, or Elon Musk. WhatsApp doesn&#x27;t need to fanout a message to millions of consumers, millions of times a day (and with multi-second latency to boot!).<p>WhatsApp also doesn&#x27;t provide a CDN, mobile analytics&#x2F;monetization&#x2F;debugging platform. WhatsApp also doesn&#x27;t contribute to open source like Twitter does (Storm, Bootstrap, Aurora).<p>Describing twitter as a &quot;140-char&quot; mailing list is very reductionist. OTOH WhatsApp problem is very well served by Erlang&#x2F;Mnesia an open source distributed messaging library developed by <i>telecommunications</i> company who were likely doing WhatApp-scale 10 yeas before WhatsApp came around. While WhatsApp engineers are great, there is very much a &quot;standing on the shoulders of giants&quot; - giants who have well researched the problem of building a system that lets two or three individuals communicate. There wasn&#x27;t anyone doing Twitter 10 years ago (well, maybe Google).<p>I don&#x27;t mean to imply that Twitter is an efficient well oiled machine, but the comparison to WhatsApp is daft.