Twitter retroactively changes developer agreement to ban third-party clients

"Long-standing" can apparently mean "later this week" at Elon Musk's Twitter, as the company has changed its developer agreement to seemingly justify its banning of third-party clients. The change happened two days after a vague tweet about "enforcing long-standing API rules" without pointing to any.

As noted by Internet sage Andy Baio, a text comparison (diff check) of Twitter's developer agreement between the effective dates of October 10, 2022, and January 19, 2023, shows only one change besides the effective date: a new line added to the section "Restrictions on Use of Licensed Materials." The addition restricts the ability of developers to:

c) use or access the Licensed Materials to create or attempt to create a substitute or similar service or product to the Twitter Applications;

With that, Twitter put an end to an era, one in which third-party clients not only coexisted with Twitter's official app—originally based on Tweetie, an early third-party app itself—but often introduced and drove new features. Twitter's official apps and its website are now the only reliable ways to access the service.