Use the free TOML to JSON Converter below: your data never leaves your browser — all work happens on your device, and nothing is uploaded to any server.
Why TOML Needs Converting to JSON
TOML is the config language of modern developer tools. Rust projects store their settings in Cargo.toml, Python projects use pyproject.toml, and static site generators, bundlers, and deployment tools all read TOML files. It is easy for humans to read: sections in square brackets, plain key and value pairs, and comments that explain what each setting does. JSON, on the other hand, is the language that APIs, JavaScript programs, and most web services speak. When a tool that only understands JSON needs to read your TOML config, you need a converter, and that is exactly what the tool above does.
The conversion is not just a cosmetic change. TOML and JSON organise data differently. TOML groups settings into tables, which look like sections with headers. JSON groups data into nested objects with braces. TOML supports dates as a native type, while JSON represents dates as strings. TOML comments vanish in JSON, because JSON has no comment syntax at all. A good converter handles all of these differences silently, so you get clean JSON that any program can parse without surprises.
How to Use the Converter
Paste your TOML into the input box and press Convert to JSON. You can choose an indent of two or four spaces, depending on the style your project uses. The output appears below, ready to copy or download as a file. If your TOML has a syntax error, the tool reports it instead of producing broken JSON, which saves you from chasing a mysterious failure in another program later.
Try the sample first if you are new to TOML. It shows a small application config with a title, a version, a debug flag, and two sections: one for the owner and one for the server. Notice how the sections become nested objects in the JSON output, and how the list of tags stays a list. That mapping is the heart of the conversion, and once you see it on a small example, larger files make sense immediately.
What Converts Cleanly, and What to Watch
Most TOML converts without any trouble. Strings, integers, floats, booleans, arrays, and nested tables all have direct JSON equivalents. Dates and times become ISO date strings, which is the standard way to write a date in JSON and the format most parsers expect. Multi-line strings collapse into ordinary JSON strings with escaped line breaks, which look messier but mean exactly the same thing.
Two things deserve attention. First, TOML allows the same key to be defined in a dotted form, like server.host, and the converter folds that into a nested object just as TOML itself does. Second, very large integers can lose precision in JSON, because JSON numbers are double-precision floats in most languages. If your TOML contains IDs or timestamps stored as huge integers, check them in the output before you rely on them. For ordinary config values, this is never a problem.
Real Situations Where This Helps
Suppose you manage a Rust project and your deployment dashboard only accepts JSON. Instead of retyping your Cargo.toml settings by hand, and risking a typo in a version number or a port, you convert the file and paste the result. Suppose you write documentation and want to show the same config in both formats side by side. Suppose a JavaScript build script needs to read settings that a Python tool wrote as TOML. In each case, the converter removes a manual, error-prone step.
It also helps when you are learning. Reading your own TOML next to its JSON equivalent teaches you both formats at once. You see how a TOML table becomes a JSON object, how an array of tables becomes a list of objects, and how inline tables work. Students and new developers often find this side-by-side view clearer than any written explanation.
Frequently Asked Questions
Is my data uploaded anywhere? No. Parsing happens in your browser with the smol-toml library. Your config never leaves your device.
What happens to TOML comments? They are dropped, because JSON cannot represent comments. Keep your original TOML file if the comments matter.
Can I convert JSON back to TOML? That is a different conversion, and this page only goes in one direction: TOML in, JSON out. Converting back needs care with types, because JSON cannot tell a date string from an ordinary string.
Use the converter above whenever a JSON-only tool meets a TOML config. It is fast, private, and it keeps your settings exactly as you wrote them.
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