YAML ⇄ Properties Converter
Convert a Spring Boot application.yml to application.properties and back — dot-notation keys, array indexes, and nested maps handled both ways.
About this tool
Spring Boot reads the same configuration from two file formats: the hierarchical application.yml and the flat application.properties. Teams often mix both, and reviewers frequently need to see one format expressed as the other. This converter turns YAML into dot-notation properties and rebuilds YAML from properties without you re-typing a single key.
It understands the tricky parts that trip up naive find-and-replace: nested maps become dotted keys, list items become indexed keys like servers[0].host, and scalar quoting is preserved so a value such as 3.10 stays a string instead of collapsing into a number. Everything is parsed and converted in your browser.
How to use
- Pick the direction you need — YAML to Properties, or Properties to YAML.
- Paste your application.yml or application.properties content into the input panel.
- The converted output appears instantly in the right panel; there is no button to press.
- Check how nested keys and list indexes are rendered in the target format.
- Use the copy button to grab the result and drop it into your config file.
- Switch the direction and paste the output back to sanity-check a round trip.
Features
- Two-way conversion between YAML and Java .properties in one place.
- Nested maps expand to dot-notation keys (spring.datasource.url) and collapse back.
- YAML sequences map to indexed keys (items[0], items[1]) and reconstruct correctly.
- Preserves quoted values so version-like strings are not silently turned into numbers.
- Comments and blank lines are handled gracefully instead of breaking the parse.
- Tuned for real Spring Boot config, not just abstract key-value data.
- Runs fully client-side — your configuration never leaves the browser.
Frequently asked questions
Does my configuration get uploaded anywhere?
No. Parsing and conversion happen entirely in your browser with JavaScript. Nothing is sent to a server, which matters because config files often contain credentials and connection strings.
How are YAML lists converted to properties?
Each list element becomes an indexed key. A YAML sequence under servers turns into servers[0], servers[1], and so on, which is exactly how Spring Boot binds indexed properties back into a collection.
Will it keep my values as strings when needed?
Yes. Quoted YAML scalars are preserved so a value like "1.10" stays a string rather than being interpreted as the number 1.1, which is a common source of config bugs.
Can I convert properties back into YAML?
Yes. Choose the Properties to YAML direction and dotted keys are re-nested into a hierarchy, with indexed keys rebuilt as YAML lists.
Is this only for Spring Boot?
It is tuned for Spring Boot conventions, but any tool that reads standard Java .properties or plain YAML key-value files will work the same way.