How do I convert JSON to a Java .properties file online?

Paste a JSON object into the input panel and click Convert. Each top-level key becomes a key=value line; nested objects are flattened into dotted keys by default. Copy the result or download it as a .properties file.

Can I convert a nested JSON object to .properties format?

Yes. With "Dotted keys → nested" enabled, a nested object such as { "app": { "name": "MyApp" } } is flattened to app.name=MyApp. Disable the toggle to only accept already-flat JSON objects.

Is the output compatible with java.util.Properties?

Yes. The .properties output is generated with a properties-file-aware serializer so keys and values follow the same conventions java.util.Properties#load expects, including the standard = separator.

Will my JSON be uploaded anywhere when converting to .properties?

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

Does JSON to Properties support comments?

If your JSON has a $comments object (for example, pasted directly from Properties to JSON's output), each entry is reinserted as a # comment line above the matching key. Set Comments to "Ignore" in Advanced options to emit plain key=value lines only.

What separator is used when flattening nested JSON keys?

The default separator is a dot (.), matching standard Java properties naming conventions like app.cache.ttl. You can change it in Advanced options if your properties file uses a different convention.

How are booleans and numbers written out in the .properties output?

JSON booleans and numbers are written as their plain text form — true, false, or the number itself — matching how the Properties to JSON converter reads them back with type inference enabled.

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 this tool converts it into Java .properties format instantly in your browser. Nested objects are flattened into dotted keys (or kept as-is if you disable nesting), and any $comments field produced by the Properties to JSON converter is reinserted as # comment lines above the matching key. Nothing is uploaded — the conversion runs entirely client-side.

JSON Input

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.properties Output

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About the JSON to Properties Converter

This is the reverse of Properties to JSON: it takes a JSON object — flat or nested — and writes it out as a Java .properties file compatible with java.util.Properties#load. Nested objects like { "server": { "port": 8080 } } become dotted keys such as server.port=8080 when dotted-key flattening is on; turn it off to require already-flat keys. If the JSON includes a $comments object (as produced by pasting output from Properties to JSON), each entry is written back as a # comment line directly above its key, so a round trip through both tools keeps the file's documentation intact.

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How to convert JSON to .properties

1
Paste your JSON object
Enter a JSON object into the input panel, or click the flask icon to load a sample with a nested object.
2
Choose flattening and comment behavior
Open Advanced options to set the dotted-key separator or disable flattening, and to choose whether a $comments field is written back as # comment lines or ignored.
3
Click Convert
The JSON is flattened (if enabled) and written out as key=value lines using a properties-file-aware serializer, with comments reinserted above their key when present.
4
Copy or download the .properties file
Copy the output or download it as a .properties file ready to drop into your Java resources. Use the switch-direction icon to jump back to Properties to 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

How do I convert JSON to a Java .properties file online?: Paste a JSON object into the input panel and click Convert. Each top-level key becomes a key=value line; nested objects are flattened into dotted keys by default. Copy the result or download it as a .properties file.
Can I convert a nested JSON object to .properties format?: Yes. With "Dotted keys → nested" enabled, a nested object such as { "app": { "name": "MyApp" } } is flattened to app.name=MyApp. Disable the toggle to only accept already-flat JSON objects.
Is the output compatible with java.util.Properties?: Yes. The .properties output is generated with a properties-file-aware serializer so keys and values follow the same conventions java.util.Properties#load expects, including the standard = separator.
Will my JSON be uploaded anywhere when converting to .properties?: No. All parsing and formatting happens locally in your browser via JavaScript, with no network requests involving your data.
Does JSON to Properties support comments?: If your JSON has a $comments object (for example, pasted directly from Properties to JSON's output), each entry is reinserted as a # comment line above the matching key. Set Comments to "Ignore" in Advanced options to emit plain key=value lines only.
What separator is used when flattening nested JSON keys?: The default separator is a dot (.), matching standard Java properties naming conventions like app.cache.ttl. You can change it in Advanced options if your properties file uses a different convention.
How are booleans and numbers written out in the .properties output?: JSON booleans and numbers are written as their plain text form — true, false, or the number itself — matching how the Properties to JSON converter reads them back with type inference enabled.