High-performance, NativeAOT-ready Conflict-free Replicated Data Types (CRDTs) for modern .NET.
Crdt implements the full catalogue of CRDTs — counters, registers, sets, maps, flags, graphs, trees, JSON documents, and sequence/text types — in state-based, delta-state, and operation-based flavours, with compact binary and System.Text.Json source-generated serialization. It also includes advanced/esoteric variants (bounded, resettable, and handoff counters, causal-length sets, a tree with move, Fugue, and interval tree clocks).
- Strong eventual consistency without coordination: replicas converge after exchanging state, deltas, or operations.
- Fast:
readonly structbuilding blocks,Span<T>/IBufferWriter<byte>serialization,BinaryPrimitives/Unsafefast paths, no LINQ on hot paths. - NativeAOT & trimming clean on .NET 8/9/10 — the library is annotated
IsAotCompatible, and the test suite itself is verified running as a NativeAOT binary. - Broad reach: targets
netstandard2.0,netstandard2.1,net8.0,net9.0,net10.0(polyfilled on older runtimes). - Strong-named: all assemblies are signed (public key token
da3d093ebe8bf537) for strong-named and .NET Framework consumers — see strong naming.
| TFM | Notes |
|---|---|
net10.0, net9.0, net8.0 |
Full feature set; NativeAOT supported. |
netstandard2.1 |
Compatibility target (Unity / Mono / .NET Core 3.x) via polyfills; not itself AOT-published. |
netstandard2.0 |
Broad compatibility target (.NET Framework 4.6.1+, older Unity / Mono) via System.Memory + Microsoft.Bcl.HashCode and source polyfills; not AOT-published. |
dotnet add package CrdtThe optional replication/transport layer — in-memory, TCP (with optional TLS), and UDP anti-entropy gossip, in state-based, delta-state, and operation-based modes — ships as a separate package:
dotnet add package Crdt.TransportDTLS-secured datagram gossip (built on DtlsSharp) lives in a further opt-in package:
dotnet add package Crdt.Transport.DtlsMQTT broker gossip (built on Mqtt.Client) — for replicas that reach each other through an MQTT 3.1.1/5.0 broker rather than peer-to-peer — ships as another opt-in package:
dotnet add package Crdt.Transport.MqttPeer-to-peer gossip over the nanomsg/NNG BUS scalability protocol (built on NanoMsgSharp, pure-managed, no broker) — over TCP, TLS, IPC, WebSockets, or in-process — ships as another opt-in package:
dotnet add package Crdt.Transport.NanoMsgPGM reliable multicast (built on Pgm, pure-managed RFC 3208 multicast) ships as another opt-in package:
dotnet add package Crdt.Transport.Pgm| Family | Types |
|---|---|
| Counters | GCounter, PNCounter, BCounter, ResettableCounter, HandoffCounter |
| Registers | LWWRegister<T>, MVRegister<T> |
| Sets | GSet<T>, TwoPhaseSet<T>, LWWElementSet<T>, ORSet<T>, CausalLengthSet<T> |
| Maps | ORMap<TKey,TValue>, LWWMap<TKey,TValue> |
| Flags | EnableWinsFlag, DisableWinsFlag, GFlag |
| Graphs | TwoPTwoPGraph, AddOnlyDag |
| Trees | ReplicatedTree (highly-available move) |
| Documents | JsonCrdt (nested JSON) |
| Sequences / Text | Rga<T>, LogootSequence<T>, LSeqSequence<T>, TreedocSequence<T>, YataSequence<T>, WootSequence<T>, FugueSequence<T>, Text |
| Causal clocks | HybridLogicalClock, VersionVector, IntervalTreeClock |
The Counters, Sets, Trees, Documents, Sequences, and Causal clocks rows include several advanced / esoteric CRDTs (bounded, resettable, and handoff counters; causal-length set; tree-with-move; JSON document; Fugue; interval tree clocks). See Advanced / esoteric CRDTs for what each one is for.
- State-based (CvRDT) — exchange and
Mergefull states. Robust to reordering and duplication. - Delta-state — propagate small deltas of the same lattice; converges with a causal delta protocol.
- Operation-based (CmRDT) — propagate operations carrying their causal context; effects are idempotent / de-duplicated.
Crdt provides the data structures, merge/delta/operation logic, and serialization. Wiring replicas to a network (gossip, anti-entropy, broadcast) is left to the application.
- Getting started — install, your first counter, merging replicas.
- Data types — the full catalogue with usage examples for every CRDT.
- Choosing a data type — when to use which type, when not to, and rough performance/resource cost.
- Replication models — state-based, delta-state, and operation-based, and when to use each.
- Garbage collection — causal stability, stable cuts, tombstone reclamation, and pluggable consensus.
- Serialization — the binary and JSON formats, value serializers, and hostile-input limits.
- Architecture — semilattices, dots, the causal kernel (ORSWOT), and the Hybrid Logical Clock.
- Performance & NativeAOT — AOT compliance, trimming, and benchmarking notes.
- Transports — the optional
Crdt.Transportpackage: in-memory, TCP/UDP, DTLS-secured, MQTT broker, nanomsg/NNG BUS, and PGM multicast gossip replication. - Strong naming — assembly identity and the committed signing key.
dotnet build Crdt.slnx -c Release
dotnet test Crdt.slnx -c ReleaseLinting / formatting:
dotnet format Crdt.slnx --verify-no-changes
pwsh -NoProfile -File eng/check-line-length.ps1NativeAOT test gate (publishes and runs the suite as a native binary):
dotnet publish tests/Crdt.Tests/Crdt.Tests.csproj -c Release -f net10.0 -r <rid> -p:AotTest=true