CloneBox Deep-clone any .NET object graph

Deep-clone any .NET object — or copy into another. Super easy, very fast, and it just works across the graphs you actually use. Free and open source from the makers of ETLBox.

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Why another cloner?

Flat POCOs are easy. Real graphs are not.

Cycles blow the stack. ExpandoObject comes back sharing nested instances. Dictionaries lose their key types. Mappers and JSON round-trips were never cloners — they just look like one until you check the result.

CloneBox is built for the hard cases, with an API that stays tiny: CloneX() for a deep copy, CloneXTo() for copying into a target.

using CloneBox;

var customer = new Customer {
    Id = 1,
    Name = "Ada",
    Address = new Address { City = "Berlin" }
};

var copy = customer.CloneX();
// copy is a new Customer; Address is a new instance too

Or clone into another object

CloneXTo() copies matching members onto a different type or onto an instance you already have. Extra fields on the target stay unchanged.

var source = new Customer {
    Id = 1,
    Name = "Ada",
    Address = new Address { City = "Berlin" }
};

var dto = new CustomerDto { ExtraOnTarget = "keep-me" };

source.CloneXTo(dto);
// dto.Id / Name / Address filled; ExtraOnTarget still "keep-me"

Install from NuGet and you are done — no license key, no trial, no setup beyond the package reference.

Real deep clones

CloneX() copies nested objects, collections, arrays, and dictionaries — including cycles — without shared identity.

Clone into existing objects

CloneXTo() fills a different type or an instance you already have. Extra target fields stay put.

Dynamics included

ExpandoObject and mixed graphs work the same way as typed POCOs — including clone-into a DTO.

Very fast

Built for hot paths. Competitive with specialized cloners on simple graphs — and still correct when the graph gets hard.

Benchmarks at a glance

Release / net10.0. A time is only listed when the result was correct — — means wrong output or a crash.

Library	simple	cyclic	dynamic	into	pass
CloneBox	0.35 µs	0.33 ms	1.92 µs	0.91 µs	4/4
DeepCloner	0.20 µs	0.37 ms	1.18 µs	—	3/4
FastDeepCloner	2.76 µs	—	—	—	1/4
CloneExtensions	0.17 µs	—	—	—	1/4
AnyClone	3.40 µs	—	—	—	1/4
Mapster / AutoMapper	~0.2 µs	—	—	—	1/4
Newtonsoft.Json	2.31 µs	—	—	—	1/4

Full benchmark notes

How CloneBox compares

Same libraries as above. Correctness first — speed only counts when the copy is right.

Library	cyclic	dynamic	into	Tests & maintenance
CloneBox	Yes	Yes	Yes	280+ tests, actively maintained by ETLBoxperts
DeepCloner	Yes	Yes	Limited	Mature, slower cadence
FastDeepCloner	Crash	—	—	Thin coverage, often unmaintained
CloneExtensions	—	Wrong key types	—	Thin coverage, often unmaintained
AnyClone	—	Shared nested refs	—	Thin coverage, often unmaintained
Mapster / AutoMapper	Shared refs	Fail / wrong	New instance	Mappers — not cloners
Newtonsoft.Json	Shape / key loss	Wrong	New instance	Serializer round-trip

Need more control?

Defaults cover most cases. When they don’t, CloneSettings lets you skip members, limit visibility, opt into ICloneable, or plug in logging.

var clone = source.CloneX(new CloneSettings {
    DoNotCloneProperty = p => p.Name == "Password",
    IncludeNonPublicFields = false,
    Logger = logger
});