JSON to C#
Convert between data formats instantly with this json to c#. Transform your data for different applications and programming languages.
Features
- Instant Conversion: Transform data formats in milliseconds
- Preserve Structure: Maintains data relationships and hierarchy
- Error Handling: Clear feedback on conversion issues
- Copy Output: One-click copying of converted data
Example
Input:
``
{"firstName": "John", "lastName": "Doe", "age": 30}
`
Output:
`
public class Root
{
public string FirstName { get; set; }
public string LastName { get; set; }
public int Age { get; set; }
}
`
Tips
Properties use PascalCase- Nullable types for optional fields
- Works with System.Text.Json or Newtonsoft
How to Use
1. Paste your JSON in the input area
2. Click convert to transform the data
3. Review the converted output
4. Copy or download the result
Best Practices
- Validate your source data before conversion
- Check the output for any formatting issues
- Test with a small sample before converting large files
- Keep backups of original data
JSON to a C# Class
System.Text.Json has been the built-in default since .NET Core 3.0, replacing
Newtonsoft.Json for most new work:
`csharp
public record User(int Id, string Name, List Tags);
var user = JsonSerializer.Deserialize(json);
`
The one difference that catches Newtonsoft users out: System.Text.Json is
case-sensitive by default. A JSON name will not bind to a C# Name property unless
you say so:
`csharp
var options = new JsonSerializerOptions { PropertyNameCaseInsensitive = true };
`
It is also stricter about trailing commas and comments, both of which Newtonsoft tolerated.
JSON Types in C#
| JSON | C# |
|---|---|
| object | record or class |
| array | List or T[] |
| string | string |
| number | int, long, double or decimal |
| true / false | bool |
| null | null |
System.Text.Json is case-sensitive by default, unlike Newtonsoft — set PropertyNameCaseInsensitive.Generate the Type, Do Not Hand-Write It
Deriving a type from a sample payload is a starting point and not a specification. A sample
cannot tell you which fields are optional, which strings are really enums, what the bounds
are, or which numbers are money. Treat generated types as a first draft, then:
Mark optional fields explicitly. A field absent from your sample is not necessarily
required.
- Narrow strings to unions where the API documents a fixed set.
- Widen numbers where precision matters — decimals for money, strings for large IDs.
- Decide on unknown fields. Ignoring them is forgiving; rejecting them catches API
changes early. Pick deliberately.Numbers Are the Recurring Problem
A JSON number is an IEEE 754 double. Three consequences that bite in production:
Twitter hit the first one publicly: 64-bit tweet IDs arrived in JavaScript rounded, so the
API began sending an Value What happens Integers above 2⁵³ Silently lose precision — send IDs as strings Money as a float 0.1 + 0.2 = 0.30000000000000004 Leading zeros 007 is invalid JSON; "007" is a stringNaN and InfinityNot valid JSON at all alongside every id.
Keys, Order and Duplicates
Objects are formally unordered, though every JavaScript engine preserves insertion order for
string keys — with one exception: integer-like keys sort numerically and come first.
`javascript
JSON.stringify({ b: 1, 2: 2, a: 3 }); // {"2":2,"b":1,"a":3}
`
Duplicate keys are not an error in the spec, and JSON.parse` keeps the last one. Two
parsers can legitimately disagree about which value wins, which has been the basis of real
request-smuggling attacks.