XML to JSON conversion with Json.NET

XML-to-JSON conversion is a common requirement when modernizing .NET applications: migrating from legacy XML-based services or storage to JSON-native systems like Couchbase Server or Couchbase Capella. In C#, two libraries handle this conversion: Newtonsoft Json.NET (the long-standing community standard, now at v13) and System.Text.Json (built into .NET Core 3.1+ as a lightweight alternative). This post covers the key differences between XML and JSON, how to perform the conversion using both libraries, edge cases to watch for, and how to store the resulting JSON documents in Couchbase using the .NET SDK.

XML vs. JSON: Key Differences

Characteristic	XML	JSON	Migration Considerations
Syntax	Tag-based: <name>Alice</name>	Key-value: {“name”: “Alice”}	XML tags become JSON keys
Verbosity	High: opening and closing tags	Low: minimal syntax overhead	JSON documents can be 30-60% smaller than XML equivalent
Arrays	Repeated elements: <item/><item/>	Native array type: [“a”,”b”]	Repeated XML elements
Attributes	Native: <user id=”1″>	No direct equivalent	XML attributes need a convention in the JSON object, e.g., @id or id` field in the JSON object
Human readability	Moderate: verbose but structured	High: compact and familiar to developers	JSON is generally preferred for modern APIs and document databases
Browser / API support	Declining: REST APIs prefer JSON	Universal: native in JavaScript	REST APIs almost universally use JSON; XML remains in SOAP or legacy systems

 

Option 1: Newtonsoft Json.NET

Newtonsoft Json.NET is the most widely used JSON library in the .NET ecosystem. It provides a one-line XML-to-JSON conversion via XmlNodeConverter:

Option 2: System.Text.Json (.NET Built-in)

System.Text.Json is built into .NET (Core) 3.1 and later. It does not have native XML-to-JSON conversion, but you can combine it with XDocument for a two-step approach:

This option needs a helper function:

For most XML-to-JSON migration scenarios, Newtonsoft Json.NET is the simpler choice, and is generally more feature rich. System.Text.Json would make sense for new .NET 6+ projects that are not migrating from XML and when serialization performance is critical.

Characteristic	Newtonsoft Json.NET	System.Text.Json
XML conversion	Native: SerializeXmlNode and DeserializeXmlNode	Manual: requires custom helper code
Performance	Generally adequate	Optimized for Span<T> / ReadOnlySpan<T>
Availability	NuGet package	Built into .NET Core 3.1+ / .NET 5+
Flexibility	High: extensive feature set and customization options	Moderate: opinionated, fewer extension points
When to consider	XML migration; complex serialization scenarios	New .NET 6+ projects; performance-sensitive APIs

 

Storing Converted JSON in Couchbase (.NET SDK)

Once converted to JSON, documents can be stored in Couchbase using the .NET SDK 3.x. The SDK accepts any C# object or JObject (Newtonsoft) as a document value:

For bulk migration of many XML documents, use Task.WhenAll to insert/upsert documents in parallel:

Common Edge Cases

Edge Case	Issue	Solution
Single vs. multiple child elements	A single <role> element becomes a string; multiple become an array	Force array output with JsonConvert settings or post-process the JSON
XML attributes vs. elements	Attributes get @ prefix in Json.NET output	Strip @ prefix in post-processing if not needed in Couchbase documents
XML namespaces	Namespaces appear as @xmlns keys	Strip namespaces before conversion using XmlDocument.RemoveAll() on namespace nodes
Null / empty elements	Empty XML tags become null or empty strings	Normalise to null or remove from document in post-processing
Large XML files	Loading a large XmlDocument into memory may cause out-of-memory errors	Use XmlReader for streaming conversion of large files

 

Frequently Asked Questions

How do I convert XML to JSON in C#?

The simplest approach is Newtonsoft Json.NET: load your XML into an XmlDocument, then call JsonConvert.SerializeXmlNode(doc). For .NET 6+ projects without an XML migration need, System.Text.Json is the built-in alternative. See the code examples above for both approaches.

What is Newtonsoft Json.NET?

Newtonsoft Json.NET is the most widely used JSON library in the .NET ecosystem, maintained by James Newton-King. The current version is 13.x. It provides serialization, deserialization, querying (LINQ to JSON), and XML-to-JSON conversion. Install via NuGet: Install-Package Newtonsoft.Json.

What is the difference between XML and JSON?

XML uses tag-based syntax with attributes, namespaces, and schema validation via XSD. JSON uses a compact key-value format natively supported by JavaScript. JSON documents are typically 30-60% smaller, faster to parse, and universally supported by modern REST APIs and document databases. See the comparison table above for a full breakdown.

How do I store converted JSON in Couchbase from C#? Use the Couchbase .NET SDK 3.x (NuGet: CouchbaseNetClient). Connect to your Couchbase cluster or Capella endpoint, get a reference to a collection, and call collection. UpsertAsync(documentId, jsonObject). The SDK accepts JObject (from Newtonsoft) or any .NET POCO. See the code example in the “Storing in Couchbase” section above.

Should I use Newtonsoft Json.NET or System.Text.Json? For XML migration scenarios, Newtonsoft Json.NET is the better choice – it has native XML-to-JSON conversion via SerializeXmlNode(). For new .NET 6+ projects that don’t involve XML, System.Text.Json is the preferred option: it is built in, allocation-efficient, and performs better in high-throughput scenarios.

Conclusion

Converting XML to JSON in C# is straightforward with Newtonsoft Json.NET’s SerializeXmlNode method. The main considerations are attribute handling (@ prefix convention), repeated element array coercion, and namespace stripping. Once converted, the Couchbase .NET SDK makes it simple to store the resulting JSON documents in Couchbase Capella or Server using UpsertAsync.

This blog post was inspired by an email conversation with a Couchbase user. If you have any suggestions on tools, tips, or tricks to make this process easier, please let me know. Or, contact me if there’s something you’d like to see me blog about! You can email me or contact me @mgroves on X.