Convert JSON to Properties

Yes. In keys: =, :, spaces, tabs, form-feed, backslash, leading ! and #, embedded newlines/carriage returns. In values: backslash, embedded newlines/tabs/form-feed, leading whitespace. {"a:b":"v"} correctly produces a:b=v – readable by any java.util.Properties consumer.

Dot-index items.0=a, items.1=b is the generic flattening – works with most config systems that parse dotted keys. Bracket-index items[0]=a, items[1]=b is what Spring Boot uses for @ConfigurationProperties collection binding. Pick whichever your downstream consumer expects.

Only for Java’s classic Properties.load(InputStream) path, which reads ISO-8859-1 and requires uXXXX for non-ASCII. Spring Boot, Tomcat 8+, and modern Java code that calls Properties.load(Reader) with a UTF-8 reader handle raw UTF-8 fine. Leave off unless you specifically need legacy compatibility.

Mostly yes – but properties files are typed as strings, so the decoder applies smart coercion: "42" → 42, "true" → true, "null" → null. Round-tripping {"a":"42"} through properties and back gives {"a":42} – the original string-ness is lost. For exact round-trips, keep the JSON.

The decoder collects all lines starting with # or ! as comments. With “Include parsed comments” enabled, they’re emitted under a __comments__ array key in the output JSON. Without it, comments are dropped but the data is preserved. Encode mode supports a single header comment.

JSON’s null doesn’t map cleanly to Java properties (which has no null concept – every key has a string value). Three modes: empty writes key= (most common, treated as empty string in Java), skip omits the line (closer to “unset”), literal writes key=null (so your code sees the four-character string “null”).

Yes, arbitrary depth. {"a":{"b":[{"c":1}]}} flattens to a.b.0.c=1 (dot mode) or a.b[0].c=1 (bracket mode). The decoder uses a heuristic: numeric path segments create arrays, others create objects.

The decoder honors Java’s line-continuation rule: a line ending in a single backslash continues onto the next line, with leading whitespace stripped from the continuation. Two backslashes at the end is an escaped backslash, not a continuation.

No. All escaping, flattening, parsing, and JSON manipulation runs in your browser. Open DevTools → Network and watch zero requests fire after the page loads. Safe for application config files, secrets, or any sensitive data.

Yes. Total bundle is under 20 KB. Once the page loads, disconnect and keep converting – useful when working with config files in air-gapped environments.