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Converters

JSON vs. CSV vs. XML vs. YAML: Which Data Format to Use

Last updated: 2026-06-13

Pick the format that matches the shape of your data and who will read it. CSV is for flat tables, JSON is for structured data and APIs, YAML is for human-edited config, and XML is for document-style or legacy enterprise data. The wrong choice forces awkward conversions later — and some conversions quietly lose information.

The four, at a glance

  • CSV — rows and columns, nothing more. Opens in any spreadsheet, has no nesting and no real data types (everything is text).
  • JSON — nested objects and arrays with basic types (string, number, boolean, null). The lingua franca of web APIs.
  • YAML — the same data model as JSON but indentation-based, with comments. Built for humans to hand-edit; dominant in DevOps config.
  • XML — elements plus attributes, verbose, schema-validated. Common in documents, SOAP services, and older enterprise systems.

Choosing quickly

  1. Flat tabular data headed for a spreadsheet or a colleague in finance? CSV.
  2. Talking to a web API or storing nested records? JSON.
  3. A config file people will edit by hand (CI pipelines, Kubernetes)? YAML.
  4. Interoperating with a legacy/enterprise system or marking up a document? XML.
Try the toolJSON ⇄ CSV ConverterConvert JSON to CSV and CSV to JSON in your browser — nested objects flattened to dot-notation columns, delimiter options, and file download.

What gets lost in conversion

Conversions between these formats are not always lossless, and knowing where the edges are saves debugging:

  • JSON to CSV flattens structure — nested objects and arrays have to be flattened into columns or serialized into a cell, because CSV cannot nest. The JSON to CSV converter handles the common flattening for you.
  • CSV to JSON must guess types — is 007 a number or a string? Is TRUE a boolean? CSV stores everything as text, so the reader infers.
  • XML to JSON has to decide how attributes map — the XML to JSON converter folds attributes into the object, but the round-trip back to identical XML is not guaranteed.
  • YAML to JSON drops comments — JSON has no comment syntax, so YAML's notes vanish. The YAML to JSON converter preserves the data but not the commentary.

A note on YAML and whitespace

YAML's readability comes from significant indentation, which is also its sharpest edge: a stray tab or an extra space changes meaning or breaks the parse. If a YAML file misbehaves, suspect invisible whitespace before anything else.

Frequently asked questions

Should I use JSON or CSV?

Use CSV for flat, spreadsheet-style tables and JSON for nested or structured data and API payloads. CSV cannot represent nesting; JSON can.

Why use YAML instead of JSON for config?

YAML supports comments and is easier to hand-edit thanks to indentation-based syntax, which is why config-heavy tools favor it. JSON has no comments and is noisier to edit by hand.

Is converting JSON to CSV lossless?

Not necessarily. CSV cannot nest, so nested objects and arrays must be flattened or serialized into cells, which can lose or reshape structure.

Why does my YAML file fail to parse?

Usually indentation: YAML treats whitespace as significant, so a stray tab or misaligned space changes the meaning or breaks the parse. Check for invisible whitespace first.

Tools in this guide