Sensor Tower: Bluesky had 628K mobile downloads in April 2023, up 606% from March, when its Android app launched, in addition to iOS; Mastodon had 90K downloads
Context & Ripple Effects
Bluesky's April surge is the first hard read on what happens once the invite-only experiment opens up: after 245K cumulative iOS installs by late April following the waiting-list opening, adding an Android app in March turned a trickle into 628K monthly downloads. Sensor Tower's same-month framing matters — Mastodon managed only 90K downloads against Bluesky's 628K.
The comparison also lands next to Sensor Tower's Twitter Blue tally of 385K subscribers and $11M mobile revenue, which showed where X was putting its energy at exactly the moment its decentralised rivals were fighting for installs.
First-order effects
- Bluesky exits April with a sixfold month-over-month download jump driven by the new Android app, converting it from an iOS-only beta into a two-platform contender while still invite-gated.
- Mastodon's 90K downloads in the same month show the open-protocol alternative ceding the 'leave Twitter' default position to Bluesky despite arriving earlier.
Second-order effects
- X faces a widening funnel problem: every Bluesky install wave gives disaffected users a ready landing spot, pressuring Twitter's subscription-led strategy that Sensor Tower pegged at just 385K paying users.
- Mastodon's underperformance forces a positioning choice between competing head-on for ex-Twitter users and doubling down on communities Bluesky isn't serving.
Third-order effects
- If the pattern holds across the coverage — 1 million downloads by July 2023, a post-election surge past 20 million users, then the 27% MAU decline Similarweb measured in mid-2026 — decentralized Twitter rivals are wave-riders whose audiences swell with each X controversy and drain when it recedes, rather than building durable replacement networks.
The trend: Decentralized social networks are riding episodic waves of X user flight rather than compounding steadily, with Bluesky's install spikes tracking Musk-era controversies instead of organic retention.