Convert JSON to CSV, YAML, XML, TOML, or Python online

One click turns JSON into CSV, YAML, XML, TOML, NDJSON, or Python — and back. Yellorn flags lossy conversions before they happen, so you're never surprised.

Convert in one click

Open a file in any text format — JSON, JSON Lines (NDJSON), XML, YAML, TOML, CSV, or ASCII Table — and the editor toolbar's Format selector menu lists every other format you can switch to. Pick one and the text is rewritten and the active format switches, all at once.

It's fast because the hard part is already done: your document is parsed once into a shared shape, and converting just re-serializes that shape into the target format.

The Format selector open on a JSON tab, listing JSON Lines, XML, YAML, TOML, CSV, ASCII Table, and Python with Convert rows — including a Lossy chip on CSV and ASCII Table — One toolbar menu lists every conversion target — lossy ones (CSV, ASCII Table) are flagged before you click.

Editor tab after clicking YAML in the Convert menu — the format selector now reads YAML, the editor shows the same two orders re-serialized as indented YAML with nested items lists, the status bar reads Valid YAML, and the tree view on the right is unchanged — Click YAML and the text rewrites in place — same two orders, same nested items lists, now valid YAML. The tree view never blinks because it's the same underlying data.

What converts to what

Text formats (JSON, NDJSON, XML, YAML, TOML, CSV, ASCII Table) convert both ways — any one to any other.
Python is a conversion target: get a ready-to-run dict/list literal (or an idiomatic loader snippet for XML/YAML/CSV).
Binary & AI files (Parquet, Arrow, Excel, MessagePack, CBOR, Protobuf, BSON, gzip, Safetensors, GGUF, ComfyUI) are sources only — drop one in and convert its decoded contents out to any text format.

Lossless vs lossy — and the warning

Conversions between the hierarchical formats (JSON ↔ YAML ↔ XML ↔ TOML) keep your data intact. Some target formats have a stricter shape, so if your data doesn't fit, Yellorn shows a “Convert anyway?” warning that explains exactly what would change:

→ CSV / ASCII Table want a flat list of rows. Nested values get JSON-stringified into the cell.
→ XML needs a single root, so a top-level list or multiple keys get wrapped under <root>.
→ TOML has no null type and no top-level array, so nulls are dropped and arrays are wrapped under a root key.

Clean, fitting data converts with no warning at all.

Undo is atomic

A conversion is a single step on the undo stack. One Ctrl/Cmd+Z restores both the previous text and the previous format together — so it's always safe to try a conversion and step back.

Frequently asked questions

How do I convert JSON to CSV online?

Open the JSON in Yellorn and pick CSV from the Format selector (Convert rows) in the editor toolbar. Yellorn flattens the array of objects into rows and columns; if the data is nested it warns you first that nested values will be JSON-stringified into cells. The conversion runs in your browser.

Can I convert CSV back to JSON?

Yes. Cross-format conversion is bidirectional across all text formats — open a CSV and convert it to a JSON array of row objects, or to YAML, XML, or TOML, in one click.

Is the conversion lossless?

Conversions between hierarchical formats (JSON, YAML, XML, TOML) preserve your data. When a target format is stricter — CSV wants flat rows, XML needs a single root, TOML has no null type — Yellorn shows a 'Convert anyway?' warning explaining exactly what would change before you commit.

Can I convert JSON to YAML and back?

Yes. JSON ↔ YAML is lossless in both directions because both can represent the same structure. Use the Format selector (Convert rows) to switch; a single undo restores the original text and format together.

Is my data uploaded when I convert it?

No. Conversion operates on the already-parsed value in memory and runs entirely in your browser. Your data is never sent to a server.

← All help articles · Pick a data format · JSON Lines (NDJSON) · Fix broken JSON · Visualize data · Open binary files · Usage guide

Where to go next

Try a fix in the editor or browse more articles.

Open editor All articles Usage guide About Yellorn