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Properties to YAML Converter

Paste a Java .properties file such as Spring Boot's application.properties and get a clean nested application.yml, or switch direction to flatten YAML into key=value properties. Escapes, \uXXXX characters, line continuations, list indexes and #--- profile documents are all handled.

Last updated: October 24, 2026

YAML indent

String quotes

Numbers & booleans unquoted Indent lists under keys Live update

.properties input

Open .properties

YAML output

Runs entirely in your browser; your configuration is never uploaded. Spring Boot #--- separators become YAML --- documents and back. Tip: Ctrl + Enter converts.

How to use the Properties to YAML Converter

Choose the direction: Properties → YAML or YAML → Properties.
Paste your file, drop it on the input or press Open. A Spring Boot sample is loaded to start.
Adjust the output: YAML indent and quoting, or separator and ASCII escaping for properties.
Check the result; conflicts and duplicates are listed under the editors and syntax errors show the exact line.
Copy or download application.yml or application.properties, or press Swap direction to convert back.

Example: application.properties and application.yml

application.properties application.yml

application.properties	application.yml
`server.port=8080 spring.datasource.url=jdbc:h2:mem:db spring.datasource.username=sa app.origins[0]=https://a.com app.origins[1]=https://b.com #--- spring.config.activate.on-profile=prod server.port=443`	`server: port: 8080 spring: datasource: url: jdbc:h2:mem:db username: sa app: origins: - https://a.com - https://b.com --- spring: config: activate: on-profile: prod server: port: 443`

server.port=8080
spring.datasource.url=jdbc:h2:mem:db
spring.datasource.username=sa
app.origins[0]=https://a.com
app.origins[1]=https://b.com
#---
spring.config.activate.on-profile=prod
server.port=443

server:
  port: 8080
spring:
  datasource:
    url: jdbc:h2:mem:db
    username: sa
app:
  origins:
  - https://a.com
  - https://b.com
---
spring:
  config:
    activate:
      on-profile: prod
server:
  port: 443

Properties escape sequences

In the file	Means
`\t` `\n` `\r` `\f`	Tab, line feed, carriage return, form feed
`\u00e9`	The Unicode character é
`\=` `\:` `\` (in a key)	A literal =, : or space that does not end the key
`\\`	A single backslash
`\` at the end of a line	The value continues on the next line (leading spaces there are ignored)

Why Spring Boot teams move to YAML

Less repetition: shared prefixes like spring.datasource are written once.
Real lists: - item lines instead of numbered [0], [1] keys.
Profiles in one file: --- separates documents, each activated with spring.config.activate.on-profile.
Watch out: @PropertySource cannot load YAML files, so keep a .properties file for those classes.

Validate the result with the YAML Validator, or convert environment files with ENV to JSON.

Frequently asked questions

How are dotted keys converted to YAML?

Each dot in a key starts a deeper level, so spring.datasource.url=… and spring.datasource.username=… become a spring map containing a datasource map with url and username. Keys that share a prefix are merged, which is exactly how Spring Boot reads application.yml.

How do I write lists in properties?

Use indexes in square brackets: app.origins[0]=a and app.origins[1]=b become a YAML list with two items, and app.servers[0].name=alpha creates a list of objects. Missing indexes are filled with null and reported.

Which properties syntax is supported?

Everything java.util.Properties accepts: key=value, key: value or key value separators, # and ! comment lines, backslash at the end of a line to continue, escaped separators in keys like my\ key, and escapes \t, \n, \r, \f and \uXXXX. Duplicate keys use the last value, like Java.

What happens when a key is both a value and a parent?

YAML cannot give one key both a value and children. If a.b=1 appears after a=x, the second key is written as a quoted "a.b" key next to a, which Spring Boot still binds to a.b. If the parent value comes after its children it is skipped and reported.

How does YAML → properties work?

The YAML is parsed (anchors and merge keys included), then every leaf value is written as a full dotted key. Lists become [0], [1] indexes, null becomes an empty value and multiple --- documents are separated with Spring Boot's #--- marker. Values are copied exactly as written, so 1.0 stays 1.0.

Do I need to escape non-ASCII characters?

Since Java 9, .properties resource bundles are read as UTF-8 and Spring Boot reads application.properties as UTF-8, so é or ☀ can be written directly. Tick Escape non-ASCII as \uXXXX for older tools that expect ISO-8859-1.

Is my configuration uploaded?

No. Both conversions run in JavaScript in this page, so passwords and connection strings never leave your device.

Are all the tools on FreeToolCabin tested for quality and accuracy?

Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.

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