Java .properties File Formatter

Clean up and standardize any Java .properties file in your browser. Paste messy configuration — mixed =, :, and whitespace separators, inconsistent spacing, duplicate keys, wrapped continuation lines — and get back a tidy, consistently formatted result you can copy or download as application.properties.

Java .properties files store configuration as flat key=value pairs and are used everywhere in the JVM ecosystem: core Java SE, Spring Boot, Logback, Hibernate, and ResourceBundle for internationalization. Because the format is so permissive, real-world files drift into three or four different styles at once. This formatter parses them the way the JVM's own Properties.load does, then re-emits everything in one clean style.

How to use it

1. Paste your .properties content into the input box (or click Try an example).
2. Pick a Separator (=, :, or preserve the original) and the Spacing around it.
3. Choose how to handle Comments and toggle any of: sort keys, remove duplicates, align separators, collapse blank lines.
4. Copy the formatted output or download it.

Everything runs entirely in your browser — your configuration never leaves your device, which matters when a properties file holds database URLs, credentials, or API keys.

What it understands

• Separators. A key and value may be separated by =, :, or a run of whitespace. The tool detects the first unescaped separator, so an escaped \= or \: correctly stays part of the key.
• Comments. Lines whose first non-blank character is # or ! are comments. You can preserve them, normalize them all to one marker, or strip them entirely.
• Line continuations. A line ending in a backslash (\) continues onto the next physical line; the tool joins them into a single logical entry and drops the continuation's leading whitespace, exactly like the JVM.
• Escapes and Unicode. Escape sequences such as \n, \t, \\, and \uXXXX Unicode escapes are preserved verbatim — the tool reformats layout, it does not decode values, so your file stays byte-for-byte correct where it counts.

Formatting options

• Sort keys alphabetically — reorders entries; any comment directly above a key travels with it.
• Remove duplicate keys — keeps the last occurrence, matching how Properties.load resolves collisions.
• Align separators into a column — pads keys to equal width so every = lines up.
• Collapse multiple blank lines — reduces runs of empty lines to one.

Trailing whitespace is always trimmed from emitted lines.

Is this the same as an INI formatter?

No. Unlike INI, .properties has a flat namespace with no [section] headers — hierarchy is expressed through dotted keys like spring.datasource.url. The parser here follows the Java specification rather than INI conventions.

Does it validate my file?

It's lenient by design: it best-effort formats whatever you paste and never rejects input, so you can use it on partial or in-progress files.