Use the free Key Value to JSON Converter below: your data never leaves your browser — all work happens on your device, and nothing is uploaded to any server.
Settings, configs, and simple data often arrive as lines of text in the form key=value. An export from an old system, a list of form answers, or a notes file may hold dozens of such lines. Code, APIs, and modern tools, however, usually want JSON, the structured format with braces, quoted keys, and typed values. Converting by hand is slow and error-prone. The Key Value to JSON Converter turns those lines into a JSON object in one step.
The format is simple on purpose. Each line holds one key, a separator, and one value. The default separator is the equals sign, but a colon option covers lines like city: Madrid. Keys are trimmed of extra spaces, so city = Madrid works the same as city=Madrid. Values keep their text unless type detection is on, in which case numbers become real numbers and the words true and false become real booleans. That typing matters, because JSON with the string “31” behaves differently from JSON with the number 31 in most programs.
To use it, paste your lines into the box, one per line. The sample shows names, a number, a boolean, and a decimal. Choose the separator, leave type detection on unless you need everything as text, and leave pretty-printing on for readable output. Press Convert to JSON. The result appears below with two counts: how many keys were converted and how many lines were skipped.
Skipped lines deserve attention rather than alarm. A line without the separator cannot be split into a key and a value, so it is counted and left out. A line with an empty key is skipped the same way. Blank lines are ignored quietly. If many lines are skipped, the separator is usually wrong: a file that uses colons will fail almost entirely under the equals setting, and switching the separator fixes it at once.
Duplicate keys follow the rule most config parsers use: the last value wins. If your file lists city=Madrid and later city=Sevilla, the JSON holds Sevilla. That rule is convenient for overrides, but it can hide a copy-paste mistake, so check the key count against your line count when duplicates are possible. If the counts differ more than your blank lines explain, a duplicate is likely hiding in the file.
JSON output from this tool is a single flat object, not a nested structure. Lines cannot express nesting, lists, or quoted commas, and the tool does not pretend otherwise. If your data needs nested objects or arrays, build that structure in a JSON editor after this first conversion. For flat settings, form answers, and simple exports, a flat object is exactly the right shape.
People use this converter to turn old exports into API payloads, to prepare settings for a script, to clean survey answers into a structured file, and to teach the shape of JSON from data they already understand. Because the work happens in the browser, even files with private values never leave the device, and closing the page clears the paste from view.
How to convert key-value lines to JSON
- Paste your lines, one key-value pair per line.
- Choose the separator your file uses, = or :.
- Leave type detection on unless you need all values as text.
- Press Convert to JSON and check the key and skipped counts.
- Press Download JSON to save the result.
Frequently asked questions
Why is my number still text? Type detection may be off, or the value may hold spaces or symbols that stop it being a plain number. Clean the value and try again.
What happens with duplicate keys? The last value wins, like most config parsers. Check the key count if you suspect duplicates.
Can it make nested JSON? No. Flat lines produce a flat object. Add nesting afterwards in a JSON editor.
Is my data uploaded? No. Everything runs in your browser, and nothing is sent or stored.
Paste the lines, get the JSON, and move on to the work that actually needs the data. That is the whole point of a converter this small.