Which characters are escaped?

A space in a key, = and : inside values, and line breaks are written with a backslash—for example a\ b=x\=y and note=line1\nline2—which are exactly the escapes java.util.Properties decodes when it loads the file.

Are non-ASCII characters written as \uXXXX escapes?

No, they are written as plain UTF-8. Java 9 and later load .properties resource bundles as UTF-8, but java.util.Properties#load(InputStream) assumes ISO-8859-1, so read the file with load(Reader) and a UTF-8 reader if your code uses that API.

Can I generate Spring Boot application.properties from JSON?

Yes. Spring Boot uses dotted property names, so { "server": { "port": 8080 } } becomes server.port=8080 with the default dot separator.

What happens to JSON arrays?

An array is written as a single value containing its JSON text, such as hosts=["a","b"]. Spring Boot's indexed form (hosts[0]=a) is not generated.

How are booleans and numbers written?

As plain text—true, false, or the number—since .properties values are always strings. Properties to JSON turns them back into real JSON types when type inference is on.

Does JSON to Properties write comments?

Yes. Entries in a $comments object, such as the one Properties to JSON produces, are written as # lines above the matching key. Set Comments to "Ignore" to output key=value lines only.

Is my JSON uploaded anywhere?

No. All parsing and formatting happens locally in your browser, with no network requests involving your data.

JSON to Properties Converter

Convert a JSON object to Java .properties format, with nested-object flattening and comment reinsertion. Client-side only.

Paste a JSON object and get a Java .properties file that java.util.Properties and Spring Boot can load. Nested objects become dotted keys such as server.port=8080, separators and line breaks are escaped with a backslash so values survive the round trip, and a $comments map is written back as # comment lines. Conversion runs in your browser; nothing is uploaded.

JSON Input

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.properties Output

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About the JSON to Properties Converter

A .properties file is line-based, so the serializer escapes anything that would change how Java splits a line: a space in a key becomes \ , an = or : inside a value becomes \= or \:, and a line break becomes \n. Keys and values are joined with =, and nested JSON objects are flattened into dotted keys in their original order. Non-ASCII text such as café is written as UTF-8 rather than \uXXXX escapes; Java 9 and later read resource bundles as UTF-8, but Properties.load(InputStream) decodes ISO-8859-1, so load the file through a UTF-8 Reader in your own code.

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How to convert JSON to .properties

1
Paste a JSON object
Enter an object in the input panel or load the { "server": { "port": 8080 } } sample with the flask icon; top-level keys become property names.
2
Set the key separator
Advanced options lets you keep the Java-style dot used by names like spring.datasource.url, pick another separator, or turn flattening off so nested objects stay as JSON text.
3
Click Convert
Every leaf becomes a key=value line, with spaces in keys, separators in values, and line breaks backslash-escaped so java.util.Properties reads the same values back.
4
Save it as .properties
Copy the output or download a .properties file for src/main/resources, and use the switch-direction icon to parse it back into JSON.

References

Java SE — java.util.Properties
The official Java API documentation defining the .properties file format this converter's output targets.
RFC 8259 — The JSON Data Interchange Format
The IETF specification for the JSON input format this tool parses.

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JSON to Properties FAQ

Which characters are escaped?: A space in a key, = and : inside values, and line breaks are written with a backslash—for example a\ b=x\=y and note=line1\nline2—which are exactly the escapes java.util.Properties decodes when it loads the file.
Are non-ASCII characters written as \uXXXX escapes?: No, they are written as plain UTF-8. Java 9 and later load .properties resource bundles as UTF-8, but java.util.Properties#load(InputStream) assumes ISO-8859-1, so read the file with load(Reader) and a UTF-8 reader if your code uses that API.
Can I generate Spring Boot application.properties from JSON?: Yes. Spring Boot uses dotted property names, so { "server": { "port": 8080 } } becomes server.port=8080 with the default dot separator.
What happens to JSON arrays?: An array is written as a single value containing its JSON text, such as hosts=["a","b"]. Spring Boot's indexed form (hosts[0]=a) is not generated.
How are booleans and numbers written?: As plain text—true, false, or the number—since .properties values are always strings. Properties to JSON turns them back into real JSON types when type inference is on.
Does JSON to Properties write comments?: Yes. Entries in a $comments object, such as the one Properties to JSON produces, are written as # lines above the matching key. Set Comments to "Ignore" to output key=value lines only.
Is my JSON uploaded anywhere?: No. All parsing and formatting happens locally in your browser, with no network requests involving your data.