blue sky protocol

What Is the AT Protocol?

The AT Protocol is an open network protocol designed for social use cases, emphasizing three core principles: “portable accounts and data, algorithmic choice, and composable moderation.” It is commonly referred to in English as the AT Protocol, serving as the foundational protocol behind the Bluesky application. Unlike a blockchain, the AT Protocol operates as a federated network composed of multiple independent servers.

Within this system, user identities are represented by DIDs (Decentralized Identifiers). Think of a DID as your self-sovereign “internet ID card,” which is not reliant on any specific corporation. Your content and social graph are stored on a personal data server of your choosing and can be migrated to other servers without losing your posts or followers.

How Does the AT Protocol Work?

The AT Protocol functions through the coordinated use of “portable identity, personal data servers, and standardized interfaces.” Users are identified by their DID, and content is stored on Personal Data Servers (PDS). Different services synchronize and display information through open APIs.

On the identity layer, DIDs can be linked to your domain name for an easy-to-remember username or use a system-generated identifier. The essential feature is that you retain full control over your identity, rather than being dependent on a single platform. On the data layer, each account has its own data repository—similar to a portable hard drive—containing posts, likes, follows, and more.

At the network layer, servers replicate and subscribe to data using well-defined protocols. This creates a decentralized social graph that maintains both high performance and manageability.

How Does the AT Protocol Differ from Blockchain?

The AT Protocol is not a blockchain. While blockchains rely on global consensus and are optimized for value transfer and immutable records, the AT Protocol uses a federated architecture that prioritizes efficiency, privacy, and composability. Data is hosted on independently operated servers and synchronized across the network.

Both blockchains and the AT Protocol use cryptographic signatures to verify data authenticity. However, the AT Protocol does not depend on miners or global consensus. Instead, it operates more like email or ActivityPub: different providers run their own servers, and users can migrate freely between them.

Importantly, the AT Protocol does not have an official token, separating social experiences from speculative activity. Be cautious about any claims regarding “AT Protocol airdrops or tokens”—these are likely scams.

What Are the Core Components of the AT Protocol?

The AT Protocol is structured across three main layers: identity, storage, and services.

• Identity: DID acts as your decentralized identity, functioning as your online ID. It can be linked to a domain name for easier recognition.
• Storage: PDS (Personal Data Server) is like your private cloud drive. It stores posts and social relationships and supports seamless migration.
• Repository: Each account’s data repository is a structured collection of records, enabling efficient incremental sync and verification.
• Interface: Lexicon defines interface schemas—specifying request and response formats; XRPC is a lightweight remote procedure call protocol built on HTTP for inter-service communication.
• Recommendation: Feed Generator is an independent recommendation service; anyone can offer algorithms that users can subscribe to.
• Moderation: Labeler and moderation services are responsible for tagging content and enforcing policies. Both platforms and users can mix and match these options.
• Stream: Firehose delivers real-time event streams, making it easy for applications to subscribe to public updates network-wide.

Together, these components enable portable identities, data migration, and interchangeable services.

What Is Account Portability in the AT Protocol?

Account portability means you can switch providers without losing your identity or social graph. When migrating from server A to server B, your DID and follower relationships move with you—your fans can still find you seamlessly.

This is especially valuable if your service provider experiences outages, changes policies, or if your privacy or moderation preferences shift. For instance, if you post from one provider’s PDS but later want better speed or policy alignment, you can migrate to another PDS in minutes while keeping your original account and follower list.

How Does Content Recommendation Stay Open in the AT Protocol?

The AT Protocol decouples timeline generation from applications by delegating it to independent Feed Generator services. You can subscribe to different timeline algorithms instead of being subject to a single platform’s black-box recommendations.

For example, you might choose an algorithm that only shows long-form posts or one that prioritizes friend reposts. You can easily switch your feed by changing subscriptions in your client app. Developers can also publish new algorithms via open interfaces, creating an “algorithm marketplace” ecosystem.

How Do You Get Started with Registration and Usage?

New users typically follow these four steps—available through Bluesky and other compatible apps:

1. Create your identity. Choose a username—preferably linked to your own domain for easy recognition.
2. Select a personal data server. Use the default server or opt for another provider if you need greater privacy or performance.
3. Complete your profile and follow others. Your follows and followers are recorded in your personal data repository and will migrate with your account in the future.
4. Subscribe to your preferred timeline. Pick from various Feed Generators to tailor recommendation streams to your taste.

How Do Developers Get Started with the AT Protocol?

Developers can engage with the protocol through four main avenues: clients, recommendation engines, moderation tools, and hosting services.

1. Review protocol documentation and APIs. Start with Lexicon docs and XRPC examples to understand object models and calling conventions.
2. Subscribe to data streams. Use Firehose or related SDKs to access public event streams for analytics, search, or content discovery.
3. Build a Feed Generator. Implement algorithms such as keyword timelines or friend-priority feeds using the API so users can subscribe.
4. Deploy a PDS or middleware service. Offer stable personal data servers for small groups or develop moderation label services for community-driven content management.

As of late 2025, open-source tools and examples around the AT Protocol are rapidly growing, lowering entry barriers for developers.

What Risks and Compliance Issues Does the AT Protocol Face?

While returning control to users and developers, the AT Protocol introduces new challenges:

• Moderation and Compliance: An open network must balance free speech with legal requirements. Different regions have varying content regulations; moderation strategies must be both composable and enforceable.
• Spam and Phishing: Open interfaces may be abused—requiring collaborative labeling services, reputation systems, and client-side protections.
• PDS Reliability: Poorly maintained PDSs impact user experience; it’s recommended to choose migration-friendly and backup-ready hosting options.
• Identity Security: Losing or leaking your DID key compromises account control; implement robust backup and key rotation practices.
• Fake Tokens & Scams: There is no official token for the AT Protocol—be vigilant about impersonated tokens or airdrop scams. Always verify sources when funds are involved.

What’s Next for the AT Protocol?

The AT Protocol is evolving toward greater openness and composability. Expected developments include a more decentralized identity system, mature market-driven moderation and labeling collaborations, richer recommendation algorithm ecosystems, and interoperability experiments with other open social protocols. As more PDS options and tools become available, users will enjoy greater freedom to migrate between services, while developers can iterate quickly on new applications and algorithms. Overall, it seeks to find a new balance between efficiency, user control, and openness in social networks.

FAQ

What Are the Advantages of Bluesky Compared to Traditional Social Media?

Built on the AT Protocol, Bluesky’s primary advantages are user data ownership and account portability. You can export your data or switch providers at any time—without being locked into a single platform. Additionally, open recommendation algorithms offer more user choice rather than opaque content feeds determined by closed systems.

Can I Link My AT Protocol Account With Other Platforms?

The AT Protocol supports multi-account identity management via DIDs (Decentralized Identifiers), allowing you to manage multiple identities. However, accounts are independent—you cannot directly link them with Twitter or other platforms. You may add links to other profiles in your bio so followers can find you elsewhere.

Do Regular Users Need an Invite Code to Register on Bluesky?

Bluesky required invite codes during its early testing phase but has since opened registration more broadly. Visit bsky.app directly to check current sign-up policies. Once open registration is available, all you need is an email address to sign up and start posting—just like traditional social media platforms.

Will I Lose My Account If My Provider Shuts Down?

No—your account data is stored with the provider you select or on your own server—not on a centralized platform. Account portability ensures that even if your current provider shuts down, you can migrate your account to another compatible provider without interruption.

How Do I Know If Bluesky Is Right for Me?

If you value data privacy, want more control over content recommendations, or are interested in open protocols, Bluesky may be ideal for you. However, if you rely heavily on commercial features or influencer networks unique to other platforms, Bluesky’s ecosystem may not yet be mature enough for all needs—consider trying it as a supplementary platform first.