A comprehensive .NET 10 SDK for the AT Protocol. Build custom AT Protocol applications with your own Lexicon schemas, interact with Bluesky, or run your own managed PDS — all from clean, modern .NET APIs.

Source: Forgejo (canonical) · GitHub (mirror — issues & PRs welcome here)

⚠️ This repository was mainly built by a coding agent. Thorough testing has been conducted, and the maintainer (Grandiras) is a human.

The AT Protocol isn't just Bluesky — it's an open protocol where one account works across many apps. Each app defines its own Lexicon schemas and stores records in the user's Personal Data Server (PDS). ATProto.NET makes it easy to build these custom applications in .NET.

The SDK is in 0.* because, while it's near feature-complete, it's mostly vibe-coded and won't be called "stable" until it has been put through real use. There's no fixed timeline for 1.0 — the more this project gets exercised, the sooner it happens.

• Custom Lexicon support — RecordCollection<T> for typed CRUD on your own record schemas, plus QueryAsync<TOut> / ProcedureAsync<TIn, TOut> for custom XRPC methods and a public transport for sub-clients of your own Lexicons.
• OAuth & identity — full AT Protocol OAuth (DPoP, PAR, PKCE), did:plc / did:web resolution, type-safe Did / Handle / AtUri / Nsid / Tid / RecordKey / Cid.
• Bluesky, Chat, Ozone — app.bsky.* (actors, feeds, graph, notifications, rich text, video, bookmarks, drafts, age assurance), chat.bsky.* (direct and group chats), tools.ozone.* (moderation, reports, queues).
• Hosting — ASP.NET Core DI, the OAuth cookie login with per-user clients and service auth for calls from other services, Blazor components that act as the signed-in user, .NET Aspire integration, and a managed PDS — run the official Bluesky PDS or Tranquil PDS container via ATProtoNet.Aspire.Hosting and administer it with PdsAdminClient.
• Streaming — typed firehose consumer with CID/signature and Sync 1.1 inductive verification (MST inversion, per-repository chains, bounded resync), a Tap client, plus a Jetstream consumer (v1 and v2 wire protocols) with server-side collection/DID/kind filtering; both with reconnect and cursor persistence. Jetstream v2 also backfills from the network archive and cuts over into the live tail with no gap.
• Spaces (permissioned data, alpha) — AT Protocol's second data protocol: access-controlled space: records with LtHash set-hash commits, DPoP-bound space credentials, incremental sync with full-state recovery, and simplespace management — on both sides, with ATProtoNet.Server serving a space as an authority or a repo host. See Spaces.
• Repository internals — MST (including covering proofs), CAR v1 read and write, DAG-CBOR, signed commit objects, did:plc operation building, PLC directory client, P-256/K-256 crypto.
• Lexicon tooling — atproto-lexgen dotnet tool for bidirectional Lexicon JSON ↔ C#, linting (permission sets included) and diffing, and publishing schemas to and resolving them from the network; LexiconResolver resolves and verifies published schemas at run time.

dotnet add package ATProtoNet

Additional packages (ATProtoNet.Server — ASP.NET Core integration including the Aspire client integration, ATProtoNet.Server.EntityFrameworkCore — its EF Core stores, ATProtoNet.Blazor, ATProtoNet.Aspire.Hosting) and the atproto-lexgen dotnet tool are documented in the full package matrix.

The headline feature is RecordCollection<T> — strongly-typed CRUD on your own Lexicon schemas, stored in the user's PDS:

using ATProtoNet;
using ATProtoNet.Identity;
using System.Text.Json.Serialization;

// 1. Define your record type; it names its collection once
public class TodoItem : AtProtoRecord, IAtProtoRecord
{
    public static Nsid Collection { get; } = Nsid.Parse("com.example.todo.item");
    public override string Type => Collection;

    [JsonPropertyName("title")]     public string Title { get; set; } = "";
    [JsonPropertyName("completed")] public bool Completed { get; set; }
}

// 2. Connect and authenticate
var client = new AtProtoClient(new AtProtoClientOptions { InstanceUrl = "https://bsky.social" });
await client.LoginAsync("alice.bsky.social", "app-password");

// 3. Get a typed collection and do CRUD
var todos = client.GetCollection<TodoItem>();

var created = await todos.CreateAsync(new TodoItem { Title = "Buy groceries" });

await foreach (var record in todos.EnumerateAsync())
    Console.WriteLine($"[{(record.Value.Completed ? "x" : " ")}] {record.Value.Title}");

One AT Protocol account can power many such apps — todos, bookmarks, recipes, whatever — each with its own Lexicons, all stored in the same user's PDS.

Issues and pull requests are welcome on GitHub (mirrored from Forgejo). See CONTRIBUTING.md for the dev setup, test workflow, and conventions.

MIT.