Free online Java to JSON converter: paste Java objects or getters/setters and get JSON instantly. Browser-local processing, your code never leaves the machine.
TL;DR: Free online Java to JSON converter for toString() output. Supports Map, JavaBean, nested arrays. Runs locally — nothing uploaded.
For local tools, open DevTools → Network and search your input — it should not appear in requests.
Next steps
Usage Guide
Debugging a Java service means reading objects as toString() output in the logs — a wall of field=value that is hard to read, hard to diff, and unusable downstream. This tool parses Java toString (nested objects, collections, Maps) into structured JSON; paste a log sample and structure it in one click, entirely in your browser.
1. The many dialects of toString: what the parser understands
IDE-generated toString comes in dialects: Lombok @Data emits ClassName(field=value, ...); IntelliJ default templates are similar with different quoting rules; Arrays.toString yields [a, b, c]; Maps render as {k=v}; custom templates vary per team. This tool parses by general rules: field=value pairs, recursive brackets for nesting, string values preserved verbatim inside quotes. Formats it cannot recognize (custom separators, say) fail loudly — simplify the sample to a standard shape and paste again.
2. The full path from log line to analyzable data
- Copy one complete toString line from the logs (mind not truncating nested brackets).
- Paste it in; the equivalent JSON appears instantly with nested objects and collections expanded.
- To diff two requests: convert both, then run them through the JSON Diff tool for a field-by-field comparison.
- To mock for the frontend: feed the converted JSON straight into JSON-to-TypeScript generation.
3. Three parsing boundary notes
- Commas and brackets inside values: strings like value=1,234 or (a) rely on quote boundaries — Lombok quotes string values and parses most reliably; unquoted custom formats may misalign.
- Null and empty collections: null fields become JSON null and empty collections become [], matching serialization; but fields excluded by @ToString.Exclude simply disappear — check the annotation first when a field is missing.
- Circular references: toString prints ellipses or truncated text before a stack overflow; that output cannot become valid JSON — fix the cycle at the source.
4. Why structuring logs on the spot is worth it
The standard advice is to log JSON directly (logstash-logback-encoder and friends) so downstream tooling just works. But legacy systems and third-party components keep printing toString for a long time — this tool covers exactly that transition: turning human-oriented toString into machine-processable JSON without writing throwaway scripts and without shipping internal log data to any online service (the hard requirement in finance and intranet environments).
5. Typical combinations with other tools
- Convert then JSON Diff: compare the same object across production and staging environments down to the field.
- Convert then JSON-to-TypeScript/Go/Java types: recover interface shapes from real logs faster than reading code.
- Convert then JSONPath extraction: pull every id field out of a batch of converted log lines for a checklist.
FAQ
Paste the toString() output into the left panel (or load the sample), click convert, and you get standard JSON to copy or download.
The toString() method returns a string representation of a Java object, commonly shaped like {key=value} or ClassName(field=value). That format is not standard JSON, so JSON parsers cannot read it directly.
Map-style {key=value}, JavaBean-style ClassName(f=v), arrays/lists like [a, b, c], and standard JSON. Nested structures and Chinese characters are handled too. Running the output through a JSON formatter and schema validation afterwards is a good habit.
No. The conversion is heuristic and covers common literal shapes; annotations, generic type erasure, and custom serialization strategies are not restored. Very large input can make the page stutter, so validate the logic on a small sample before converting everything.
Yes. Copy the result directly, or click the download button to save it as a .json file.
No registration and no charge — the whole conversion runs browser-side, and your snippets never pass through a server.
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