Instapaper, a pioneering app for saving articles to read later, has been acquired — again. The app, which was created by developer Marco Arment and sold to Betaworks in 2013, has found a new home at Pinterest. The goal is "to accelerate discovering and saving articles on Pinterest," the company said in a statement. It will continue to operate as a standalone app, and the Instapaper team will work on both that app and on Pinterest generally. Terms of the deal were not disclosed.

As a visual search engine, Pinterest isn't often thought of as a place to bookmark written content. But in 2013 the company introduced article pins, a format that creates rich bookmarks complete with a photo and a preview of the text. The acquisition of Instapaper suggests the company believes there is more to be done there — although it's not certain how valuable that will be for Pinterest. Instapaper can be used for free or in a $30-a-year premium version; the company has never said how many subscribers it has.

How big a business can you build by time-shifting other people's articles?

It's an open question about how big a business can be built on time-shifting articles and videos. Pocket, a competitor to Instapaper that is larger by an order of magnitude, is experimenting with promoted recommendations along with a subscription service. Given its size, Instapaper was probably destined to land at a company with more money to support side projects.

"The Pinterest team is working on unique technical challenges, and their collective skill will add tremendous value to Instapaper," said Brian Donohue, Instapaper's CEO, in a statement. "Additionally, I'm personally looking forward to working on new projects and integrations within Pinterest."