One reason profitability is even within the realm of possibility is that the company finally made a hard, but smart choice toward the end of last year.
It moved off of third-party servers and built its own data center, which came online in October.
Tumblr CEO David Karp won't get specific about how much the company saved doing this, but a couple sources close to the company that we've talked to say that Tumblr's burn rate moved from $4 million to $5 million per month down to ~$2 million.
That's annual cost savings of more than $20 million per year.
Correction: An earlier version of this story said that Tumblr moved off
Disclosure: Jeff Bezos is an investor in Business Insider through his personal investment company Bezos Expeditions.