X Launches AI-Powered Custom Timelines, Adding Grok-Curated Feeds and Ad Slots

X moved another step away from user-led communities and toward algorithmic control on April 21, 2026, with the launch of Custom Timelines, a Grok-powered feature that lets Premium subscribers on iOS pin topics to the home tab and switch between topic-specific feeds. X’s head of product, Nikita Bier, said the update took “many months” to build and called it “one of the biggest changes to X.” Android support was promised “very soon.”

The company said the new feeds draw on Grok’s understanding of every post, combined with X’s personalization algorithm, to surface content from 75 topics at launch. Those topics include food, art, photography, business, finance, movies and TV. The design gives X more direct control over what users see, while also giving the platform a more finely segmented set of surfaces for attention and, potentially, advertising.

X also introduced Snooze Topics, available to Premium users on iOS and the web, which allows people to hide selected subjects such as politics or sports from the For You tab for 24 hours. The tool underscores how much of the feed experience now depends on platform settings rather than user-built communities or chronological following lists.

The shift comes as X continues to narrow the role of Communities, which had once been framed as a place for topic-based participation. In February 2025, X said community posts and replies could appear outside communities in the main feed and recommendations, non-members could reply, and community content would remain active even if a community was deleted. Social Media Today reported that X said communities were generating around 650,000 posts a day and that time spent in communities was up 600% year over year as of March 2025. Even so, X removed the communities tab from the app’s bottom navigation and replaced it with a dedicated video tab, a sign that Communities had not become a central engagement engine.

The broader direction is familiar across the social web. Bluesky and Threads have offered custom feeds since 2023 and 2024, respectively, but X is pairing that model with Grok, the xAI chatbot at the center of Musk’s AI push. Elon Musk said in August 2025 that X planned to introduce ads in Grok’s responses, tying the chatbot more directly to revenue as the company looks to offset the cost of expensive AI infrastructure. The result is a feed strategy that blends personalization, platform control and new inventory, while leaving X, not users, to decide what gets prominence.