Study finds curated ‘starter packs’ fueled rapid user growth on Bluesky

‘Starter packs’—curated user lists that new users can follow with a single click—played a key role in helping Bluesky grow to over 30 million users, according to a new study.

Launching new social media platforms is notoriously difficult, as users risk leaving familiar content and, most importantly, their established connections. This challenge has reinforced the dominance of existing platforms.

However, new research, led by computer scientists at Lancaster University, TU Darmstadt and City St George’s, University of London, reveals how Bluesky overcame this barrier using starter packs—an onboarding feature that helped Bluesky address the “cold start” problem and rapidly grow its user base.

“Our findings go beyond Bluesky: they point to a new framework for launching successful social platforms,” said Dr. Onur Ascigil, Lecturer in Computer Science at Lancaster University and Principal Investigator of the study. “Starter packs are becoming a vital onboarding strategy for the emerging social media systems that are seeking to attract users from dominant platforms.”

The researchers believe their findings could help platform designers and policymakers promote more equitable and trustworthy online spaces.

Starter packs can be created by anybody on the platform and generally aim to rapidly create new, or recreate existing, communities.

Starter packs were adopted rapidly by Bluesky users, with more than 335,000 created in the first six months of their launch, the researchers found. They accounted for up to 43% of people following others in Bluesky during peak periods, and contributed to nearly 20% of all follow relationships across the full study period, from June 2024 to January 2025. Users included in starter packs received up to 85% more followers and posted 60% more than similar users not included.

“While only 6.25% of users were members of a starter pack at the time of the study, the outsized impact of these starter packs highlights how a relatively small mechanism can significantly influence network formation and user visibility,” said Dr. Ascigil.

However, the researchers also found that starter packs tend to reinforce existing communities rather than create new ones. They help users with already-large followings grow even more. The researchers say this raises concerns about deepening popularity inequalities.

“Starter packs quickly became central to Bluesky’s network of social connections,” said Leonhard Balduf of TU Darmstadt, co-lead author of the study.

Saidu Sokoto, also a co-lead author from City St George’s, University of London, said, “We also observed risks, such as reinforcing popularity gaps and enabling misuse, including harassment or pay-for-inclusion practices. There was anecdotal evidence that some users may be paying to be added to high-visibility starter packs.”

The study also tracked spikes in Bluesky’s growth that aligned with real-world events like the US elections and changes at X (formerly Twitter). The researchers say starter packs played a crucial role during these waves of migration, helping newcomers quickly establish social connections.

“During peak migration periods—corresponding to the 2024 US elections and Twitter/X’s controversial decision to make content visible to users who had been blocked—between 20% and 40% of daily follow actions came from one-click starter pack follows,” said Dr. Ascigil.

Using machine learning, the researchers analyzed starter pack themes and found the largest communities centered around art, politics, gaming, sports, and activism. Many starter pack members were public figures such as journalists, politicians, and activists, i.e., groups that tend to rebuild influence early on emerging platforms.

The study, Bootstrapping Social Networks: Lessons from Bluesky Starter Packs, will be presented at the International Conference on Web and Social Media (ICWSM) in Copenhagen this June.