Royal Pingdom conducted an independent study of blogging services on the Web and found that Blogger was without question the most reliable. In fact, Blogger was the only service of all those tested that delivered 100% uptime.
"We included Blogger, WordPress.com, Typepad, Tumblr and Posterous in this survey. For each blogging service, we monitored the uptime of the homepage and four individual blogs, so we could see how the service as a whole performed. The tests were performed once a minute over a period of two months, Oct'15 - Dec'15. We used the Pingdom site monitoring service (of course), performing tests from multiple locations in North America and Europe," said Pingdom.
The bars in the chart below represent the average downtime per blog over these two months, based on the four blogs tested for each service.