README.md

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Object Mapping

Mapperly leads the current rating · 4 libraries · 10 scenarios

Rating

In every scenario the fastest library scores 100 points and the one allocating least scores 100 more; four times slower is half the points, and an unsupported scenario is worth nothing. Time and memory reach 1000 each here, so the maximum is 2000. See workflows/rating.md.

#	Library	Scenarios	Time	Memory	Points	Group wins
1	Mapperly	10/10	1000	1000	2000	gold in Advanced, gold in Basic, gold in Prepare
2	Mapster	10/10	576	792	1367	silver in Advanced, silver in Basic, bronze in Prepare
3	AutoMapper	10/10	464	802	1265	silver in Prepare, bronze in Advanced, bronze in Basic

How the points were earned — every scenario, with the measurements behind it

Each row is one scenario. Best is the lowest result among the rated libraries that completed it, and the points follow from the two figures beside them: 100 × √((best + step) / (result + step)), with a step of 1 ns for time and 24 B for memory. A dash means the library did not complete the scenario, and it scores nothing for it. Add the two Points columns over every scenario and you get the rating above. The same breakdown appears as a hint on any points value in the application.

1. Mapperly — 2000 of 2000

Scenario	Time	Best	Points	Memory	Best	Points
Simple Object	9.09 ns	9.09 ns	100	56 B	56 B	100
Nested Object	42.11 ns	42.11 ns	100	248 B	248 B	100
Collection	859.89 ns	859.89 ns	100	6.27 KB	6.27 KB	100
Flattening	10.48 ns	10.48 ns	100	56 B	56 B	100
Map To Existing	3.65 ns	3.65 ns	100	0 B	0 B	100
Null Handling	8.11 ns	8.11 ns	100	40 B	40 B	100
Custom Conversion	59.23 ns	59.23 ns	100	88 B	88 B	100
Polymorphic Mapping	29.11 ns	29.11 ns	100	144 B	144 B	100
Prepare Configuration	0 ns	0 ns	100	0 B	0 B	100
Prepare And Simple Map	9 ns	9 ns	100	56 B	56 B	100

2. Mapster — 1367 of 2000

Scenario	Time	Best	Points	Memory	Best	Points
Simple Object	19.54 ns	9.09 ns	70.1	56 B	56 B	100
Nested Object	60.53 ns	42.11 ns	83.7	248 B	248 B	100
Collection	1.02 μs	859.89 ns	91.9	6.27 KB	6.27 KB	100
Flattening	19.25 ns	10.48 ns	75.3	56 B	56 B	100
Map To Existing	10.95 ns	3.65 ns	62.4	0 B	0 B	100
Null Handling	27.18 ns	8.11 ns	56.9	40 B	40 B	100
Custom Conversion	87.36 ns	59.23 ns	82.6	112 B	88 B	90.7
Polymorphic Mapping	106.33 ns	29.11 ns	53	144 B	144 B	100
Prepare Configuration	20.89 ms	0 ns	0.022	2.43 MB	0 B	0.307
Prepare And Simple Map	21.43 ms	9 ns	0.068	2.56 MB	56 B	0.545

3. AutoMapper — 1265 of 2000

Scenario	Time	Best	Points	Memory	Best	Points
Simple Object	43.54 ns	9.09 ns	47.6	56 B	56 B	100
Nested Object	86.24 ns	42.11 ns	70.3	248 B	248 B	100
Collection	900.1 ns	859.89 ns	97.7	6.27 KB	6.27 KB	100
Flattening	44.7 ns	10.48 ns	50.1	56 B	56 B	100
Map To Existing	38.94 ns	3.65 ns	34.1	0 B	0 B	100
Null Handling	43.89 ns	8.11 ns	45.1	40 B	40 B	100
Custom Conversion	94.19 ns	59.23 ns	79.5	88 B	88 B	100
Polymorphic Mapping	197.52 ns	29.11 ns	38.9	144 B	144 B	100
Prepare Configuration	11.91 ms	0 ns	0.029	624.08 KB	0 B	0.613
Prepare And Simple Map	12.71 ms	9 ns	0.089	657.28 KB	56 B	1.09

Benchmark overview

Basic

More overview charts (2)

Advanced

Prepare

Compared libraries (4)

	AutoMapper 16.2.0 A convention-based object-object mapper with runtime configuration and compiled mapping plans.	Compare →
	Hand-coded Direct object mapping written in C# without a mapping library.	Compare →
	Mapperly 4.3.1 A source generator that creates readable object mapping code at compile time.	Compare →
	Mapster 10.0.14 An object mapper with runtime configuration, expression compilation, and projection support.	Compare →

Benchmark scenarios (10)

01 · Simple Object

Maps one object with scalar values to a newly allocated destination object.

02 · Nested Object

Maps an order with nested customer and address objects to a new destination graph.

03 · Collection

Maps an array of 100 objects while preserving count, order and member values.

04 · Flattening

Maps nested customer values into a flat order summary through member-path configuration.

05 · Map To Existing

Overwrites a supplied destination object and returns that same instance.

06 · Null Handling

Preserves null text, nested object and collection members in the destination.

07 · Custom Conversion

Maps string values through registered code and invariant decimal conversions.

08 · Polymorphic Mapping

Maps a base array containing cats and dogs to matching destination runtime types.

09 · Prepare Configuration

Creates the complete mapper configuration and eagerly prepares its runtime mapping plans.

10 · Prepare And Simple Map

Creates the complete mapper configuration and maps one simple object.