Bluesky is an initiative to develop a decentralized social network protocol, and an associated social networking service.

Originally spun out by Twitter, Inc., it hired its first employees in 2021, and was incorporated as an independent public benefit company the same year. Jay Graber currently serves as the company's CEO, while Twitter co-founder Jack Dorsey sits on its board of directors.

It currently operates its own social network, Bluesky Social, which is accessible via a web browser or an app for iOS and Android. The service is currently in an invite-only beta, though the company has specified plans to open it up to the general public at a later date. The service is described as being "Twitter-like."

Bluesky was described in 2021 as an initiative to develop a decentralized social network protocol, where multiple social networks, each with its own systems of curation and moderation, would interact with other social networks through an open standard. Each social network using the protocol would be called an "application". As of 2023, Bluesky operates its own official network called Bluesky Social, a centralised service running on proprietary software for its servers and client apps, whereas part of the protocol implementation has been released under MIT license. Neither the protocol nor service claimed to use blockchain technology in 2022.

Posts on the platform have been dubbed 'skeets' (a portmanteau of 'sky' and 'tweet') by frequent users, despite CEO Jay Graber pleading with users not to call them that.

The Authenticated Data Experiment (ADX), in mid-2022, was Bluesky's first early protocol release. It used personal data repositories, intended to be controlled by individual users, that social networks would optionally support. The stated purpose was to let users post messages without necessarily affecting their visibility to other users, as primary storage of the data would remain in the personal data repository while networks would handle the distribution to other users. This distinction was later described in the ATP FAQ as a division between "speech" and "reach" layers. Bluesky released a simplified version as the 'AT Protocol' in October 2022 alongside technical documentation.

Bluesky started a waitlist in October 2022 for a service that would use the protocol At the time of release, Bluesky only addressed interoperability and had not explained how it would address platform moderation and monetization. In February 2023, the Bluesky app was released for iOS as an invite-only beta, and the service was only available to users who have received an invite code, either from the company itself or from an existing user. Reviewing the app, TechCrunch described it as "a functional, if still rather bare-bones, Twitter-like experience." Later, in April 2023, it was released for Android.

After the launch of the Android app, the social network reached about 50,000 users in April 2023. The launch surfaced technical issues, including a bug which created incorrect notifications.

In May 2023, Bluesky was made open source under the MIT license, allowing the public to view and modify its source code.