System Text Json Patch

SystemTextJsonPatch is a JSON Patch (JsonPatchDocument) RFC 6902 implementation for .NET using System.Text.Json

This library tries to ease the migration from Newtonsoft.Json to System.Text.Json by providing similar API for HttpPatch requests as in Microsoft.AspNetCore.JsonPatch and Marvin.JsonPatch

• Designed as an easy replacement for Microsoft.AspNetCore.JsonPatch
• Supports .NET 6+ including .NET 10, plus netstandard2.0

Getting started

Build a patch document on the client. You can use the operations as described in the IETF document: Add, Remove, Replace, Copy, Move and Test.

List<Operation<DTO.Expense>> operations = [];
JsonSerializerOptions jsonOptions = new JsonSerializerOptions();
JsonPatchDocument<DTO.Expense> expensePatch = new JsonPatchDocument<DTO.Expense>(operations,  jsonOptions);
expensePatch.Replace(e => e.Description, expense.Description);

// serialize it to JSON
var expensePatchJson = System.Text.Json.JsonSerializer.Serialize(expensePatch);

On your API, in the patch method (accept document as parameter & use ApplyTo method)

[Route("api/expenses/{id}")]
[HttpPatch]
public IHttpActionResult Patch(
    int id,
    [FromBody] JsonPatchDocument<DTO.Expense> expensePatchDocument
)
{
      // get the expense from the repository
      var expense = _repository.GetExpense(id);

      // apply the patch document 
      expensePatchDocument.ApplyTo(expense);

      // changes have been applied to expense object
}

Deny access to properties

If you need to stop JsonPatch from reading or writing to some properties, then you can decorate them with [DenyPatch], if a patch occurs that happens to access the property then a JsonPatchAccessDeniedException is thrown.

Migration from v1

JsonPatchDocumentConverterFactory no longer needs to be set to JsonSerializerOptions. Instead JsonPatchDocument types now use JsonConvertAttribute to use the correct converter.

Performance comparison

This test deserializes a JSON patch document of 8 operations and applies the changes to a new model.

See SystemTextJsonPatch.Benchmark for more details.

BenchmarkDotNet v0.15.8, Windows 11 (10.0.26200.8117/25H2/2025Update/HudsonValley2) AMD Ryzen 9 5950X 3.40GHz, 1 CPU, 32 logical and 16 physical cores .NET SDK 10.0.201 [Host] : .NET 10.0.5 (10.0.5, 10.0.526.15411), X64 RyuJIT x86-64-v3 Job-PGIYFE : .NET 10.0.5 (10.0.5, 10.0.526.15411), X64 RyuJIT x86-64-v3

WarmupCount=2

Method	Mean	Error	StdDev	Gen0	Gen1	Allocated
SystemTextJsonPatch	3.495 us	0.0409 us	0.0362 us	0.2823	-	4.63 KB
MarvinJsonPatch	815.664 us	15.7153 us	18.7079 us	3.9063	1.9531	68.01 KB
AspNetCoreJsonPatch	14.385 us	0.2321 us	0.2172 us	2.5940	0.0610	42.56 KB