For a few years I was the Silicon Valley Necromancer, attempting to reenergize failing businesses with new technology. I was on the Delicious team at AVOS (2012-2013), whom acquired Delicious from Yahoo!. I probably know very little of the whole story...but...I can at least share some of the technical challenges that we faced.

I lead the team on the re-write that brought Delicious into the single page app (SPA) world. Most people wondered why we built the app from scratch again. The python codebase that the Yahoo! team managed, I am not sure if they started their version of the app that way or if the inherited it, but we concluded that it would be quicker to re-write the app as opposed to dissecting the exiting application codebase. This is the primary reason why stacks were canned, regardless of what others might have said. Many times rewrites require reducing features in order to build a new foundation. This is sometimes a good thing, and sometimes not.

A rewrite also gave us the opportunity to build the app as an SPA. While we made an SPA, React, Redux, Webpack, Gulp, etc. did not exist, and we definitely ended up spending more time than expected creating inferior toolsets due to the lack of options at the time.

Another major challenge we faced was that the database was sharded in such a way that if your username was "zebra" the backend would hit MySQL server 1, then 2,3,4,5,6,7,8,9, and finally 10 before returning results. If your username was "apple" you'd get a response quite quickly. I am not sure if we ever completed the migration into new shards/replicas.

There were also some random old API endpoints where we had to double encode periods in the url or the API would throw an exception. Obviously there was no documentation on for our treasure hunt to find which API endpoints had this major issue.

We didn't get any notice at AVOS before the team was moved off of Delicious to work on other projects. Perhaps we took too much time building the rewrite, or perhaps we realized there was no business model worth the time.

AVOS would later make a unilateral decision to move all projects to Angular, which was not a framework I believed would benefit my career development. I left AVOS when StubmleUpon called me and said, "hey if you can make Delicious a SPA, do you think you can make our app an SPA?"

Boy, I sure know how to pick 'em...

P.S. I will say that the Delicious team at AVOS was a very talented team and I am thankful for each day I got to work with them.

[edit] for grammar [edit ii] Since it doesn't seem clear in the comments: I'd build Delicious differently today.