An AI companion app backed by Meta is experiencing a sharp acceleration in user adoption, driven by a high-profile showcase at the company's annual developer event and a wave of favorable early reviews that highlighted both its interface design and the underlying AI capabilities powering it.

When the week began, the app known as Muse had already recorded more than 2.5 million downloads since its debut on September 8. By the time market intelligence firm Sensor Tower released its most recent estimates, that figure had climbed to over 3.4 million installs. The firm's data, however, is only current through Thursday, meaning there is an inherent lag between reported numbers and actual real-world adoption.

As a result, those figures do not yet fully reflect the momentum generated by Meta Connect, the company's annual developer conference held this week. At the event, Meta unveiled a series of forthcoming features for Muse, including the ability to video chat with the Muse avatar, Mac computer-use support, a dedicated email address, expanded third-party integrations and connectors, and planned compatibility with Meta's smart glasses lineup.

Download Figures Vary Across Intelligence Firms

Other market intelligence providers are tracking similar growth trajectories for Muse, though their specific figures differ considerably. Apptopia puts the app's cumulative download count at approximately 4.3 million, with an estimated 2.6 million of those attributed to iOS alone. The app is currently available exclusively in the United States and Canada.

A separate firm, Appfigures, places the total install count closer to 2.3 million as of Thursday, with downloads split nearly evenly between iOS and Android platforms. The variation between firms reflects differences in methodology and data sourcing rather than any single authoritative count.

Sensor Tower also tracked daily active user numbers in the immediate aftermath of Meta Connect and found that the metric rose by 27% on Wednesday, the day the conference concluded.

Early Growth Outpaced Rival AI Apps

Even before the conference provided an additional boost, Muse was already demonstrating unusually strong early performance. Sensor Tower reported that the app accumulated an estimated 2.8 million downloads within its first two weeks on major app stores. Between September 8 and September 17, Muse averaged day-over-day download growth of 55%. That figure stands in notable contrast to the early performance of competing AI applications - ChatGPT averaged 24% day-over-day download growth in its first 10 days following launch, while both Claude and Grok saw their download growth rates decline during their respective launch periods.

Muse rose to the top position on the U.S. App Store on Friday, September 18, and has maintained that ranking continuously. It similarly reached the number one spot on the Google Play Store on September 19 and has held that position since.

Meta's Cross-Platform Promotion Plays a Role

While a significant portion of Muse's growth appears to be organic, the app is also benefiting from Meta's established playbook for cross-platform promotion - the same strategy that helped its social platform Instagram Threads surpass 500 million monthly active users. Meta has been marketing Muse directly to its existing base of Facebook and Instagram users, leveraging its massive installed audience across those platforms.

However, Meta's Head of Threads, Connor Hayes, recently indicated in an interview with Business Insider that the promotional approach for Muse differs meaningfully from how Threads was marketed. Threads deals in user-generated content, which Meta can match to individual users' interests when designing cross-promotional campaigns. With Muse, the challenge and strategy is different - Meta is building promotional units designed to demonstrate specific things the AI agent can do for a given user, based on what Meta believes would be genuinely useful or relevant to that individual.

According to Sensor Tower, Meta began running in-house advertisements for Muse on September 9, just one day after the app launched. Within 10 days, Muse had received the largest share of internal advertising promotions across Meta's own properties, outpacing promotional activity for Facebook, Instagram, and WhatsApp. Meta also extended its advertising push beyond its own platforms, running campaigns on mobile ad networks and third-party social platforms including Reddit, TikTok, and YouTube.

By Tuesday, September 22, Muse had broken into the top 10 brands ranked by overall advertising spend, according to Sensor Tower's data.

Organic Demand Remains the Primary Driver

Despite the scale of Meta's promotional investment, the advertising push alone does not account for the bulk of Muse's growth. Sensor Tower's analysis found that paid advertisements for the app represented only 6% of total ad impressions recorded between the app's launch and September 19. That means the overwhelming majority of Muse's traction during its early weeks was driven by factors outside of paid promotion - including word of mouth, press coverage, and organic discovery through app store rankings.

The combination of strong organic interest, Meta's significant marketing infrastructure, and the additional visibility generated by Meta Connect positions Muse as one of the more closely watched AI application launches in recent memory. Whether that momentum translates into sustained long-term engagement will likely depend on how quickly Meta rolls out the features it announced this week and how well the product continues to meet user expectations beyond the initial novelty period.