"Twitpic will be shutting down September 25," the website's founder, Noah Everett, wrote in a blog post Thursday.
"A few weeks ago, Twitter contacted our legal demanding that we abandon our trademark application or risk losing access to their API," or application programming interface — the software that allows Twitpic and other services to operate through Twitter.
While in the latter stages of processing a trademark application for the use of the name Twitpic, Twitter "reached out to our counsel and implied we could be denied access to their API if we did not give up our mark," Everett wrote.
"Unfortunately we do not have the resources to fend off a large company like Twitter to maintain our mark, which we believe wholeheartedly is rightfully ours. Therefore, we have decided to shut down Twitpic."
Twitter recently revamped its own photo tool, but for a long time before that Twitpic was the most-used tool on the social media network to quickly post and share picture content.
But in a statement, a spokesman for Twitter appeared to dispute Everett's version of events, saying the company has no problem with Twitpic's name.
"We're sad to see Twitpic is shutting down," the spokesman said. "We encourage developers to build on top of the Twitter service, as Twitpic has done for years, and we made it clear that they could operate using the Twitpic name. Of course, we also have to protect our brand, and that includes trademarks tied to the brand."
Twitpic says it will allow users to extract all their pictures from the service up until September 25.