Why do some keys have brackets?

Without brackets, Spring would split a.b into two levels. Brackets keep a dot or space as part of one map key.

Can I convert it back?

Yes. The properties to YAML converter reads dots, [index], and [key] the same way.

No. It is converted in your browser.

Paste application.yml. The matching application.properties is written beside it.

Ctrl+Enter or ⌘+Enter runs this tool immediately.

application.yml

application.properties

Waiting for input.

Parsing stays in this browser. Input is not uploaded or saved.

Paste the contents of application.yml, or load the sample.
Read the properties. Each line is the full dotted path to one value.
Download application.properties, or paste single lines into environment-specific files.

Lists become indexed keys, such as include[0]=health. Spring reads them back as the same list.
Keys that contain a dot or a space are wrapped in brackets, such as app.map[a.b]=x, which is how Spring binds map keys.
Characters outside ASCII are written as \u escapes, and line breaks in values are written as \n.
Empty lists and maps have no properties form and are left out.
A file with several documents separated by --- is rejected. Spring profile documents need one properties file each.

include: [health, info] becomes include[0]=health and include[1]=info.

include: [health, info]

The key a.b is kept whole with brackets: app.map[a.b]=x.

app:
  map:
    a.b: x

The top level must be a mapping of keys.: Properties files need key names. Paste a YAML mapping, not a list or a single value.
Nested mappings are not allowed in compact mappings: The YAML itself is invalid, often a value on the same line as a nested key. Check the line and column shown.
This input contains 2 YAML documents.: Paste one document at a time. Each Spring profile document becomes its own properties file.

Why do some keys have brackets?: Without brackets, Spring would split a.b into two levels. Brackets keep a dot or space as part of one map key.
Can I convert it back?: Yes. The properties to YAML converter reads dots, [index], and [key] the same way.
Is the file uploaded?: No. It is converted in your browser.

Spring properties to YAML converter
Convert Spring Boot application.properties to application.yml in the browser. Dotted keys become nested YAML, and [0] indexes become lists.
YAML validator
Check YAML syntax without converting or rewriting it. Errors include a line and column when the parser provides them, and valid input is left unchanged.
YAML to JSON converter
Convert YAML configuration to readable or compact JSON in the browser. Comments are dropped, and parse errors include line and column when the parser reports them.