Tablizer

Convert YML to JSON Online

Convert a .yml file to JSON. The extension is the only difference from .yaml, and both are read the same way.

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Nothing here is uploaded. The parsing happens on this page.
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The output will appear here once there is a table to convert.

What YML is

YAML uses indentation instead of brackets. It is a superset of JSON, supports comments, and is meant to be edited by hand.

Kubernetes manifests, CI pipelines, Ansible playbooks and most modern config files.

What JSON is

JSON is a text format for nested data: objects with named keys, arrays, strings, numbers, booleans and null. It has no date type and no comments.

Every web API, most configuration files and anything that talks to JavaScript.

What changes when you convert YML to JSON

A YAML list of maps reads as rows and columns directly. Anchors and aliases are resolved before the table is built, so a repeated block arrives expanded rather than as a reference.

You choose the shape. An array of objects is the default and the one most code expects. A 2D array is smaller. Column arrays suit charting libraries. A keyed object suits lookups by id.

There is no difference between .yml and .yaml. The three-letter form is older and survives because some Windows tooling once cared about extension length. Both are the same format and both parse identically here.

Comments are dropped, because JSON has no syntax for them.

Anchors and aliases are expanded into full copies, since JSON cannot reference a value defined elsewhere.

What carries over from YML to JSON

JSON can express everything YAML holds about a table, so this conversion is about shape rather than loss.

Both formats record types, so numbers, booleans and nulls survive as themselves rather than as text.

The identifier 007 comes out of the JSON as 007. Reading it as a number would have made it 7, and an id that changes value is worse than one that stays text.

The role "Analyst, data" survives with its comma, in one cell rather than split across two. That is the first thing to check in any converted table, and the usual place a JSON file goes wrong.

The quotes around Jonah "Jo" Pryce are escaped with a backslash in the JSON.

A worked example

Three rows of staff data, with an identifier that has a leading zero, a value containing a comma, a value containing quotes and one blank cell. Those are the four places formats disagree, so they are the four places to look.

YML in
- id: "007"
  name: Halima Yusuf
  role: Analyst, data
  started: "2024-03-15"
  hours: "38.5"
- id: "012"
  name: Jonah "Jo" Pryce
  role: Engineer
  started: "2025-11-02"
  hours: ""
- id: "104"
  name: Wei Chen
  role: Manager
  started: "2023-06-30"
  hours: "40"
JSON out
{
  "staff": [
    {
      "id": "007",
      "name": "Halima Yusuf",
      "role": "Analyst, data",
      "started": "2024-03-15",
      "hours": "38.5"
    },
    {
      "id": "012",
      "name": "Jonah \"Jo\" Pryce",
      "role": "Engineer",
      "started": "2025-11-02",
      "hours": ""
    },
    {
      "id": "104",
      "name": "Wei Chen",
      "role": "Manager",
      "started": "2023-06-30",
      "hours": "40"
    }
  ]
}

Questions

How do I convert YML to JSON?

Paste your YML into the box above or drop the file onto it. Check the table in the grid, then copy or download the JSON from the output panel. It takes one step and the data never leaves your browser.

Why did my YAML value change meaning?

YAML reads several bare words as booleans. In the 1.1 spec that includes yes, no, on and off, which is why a country column containing NO for Norway can arrive as false. Quote values you want kept as text.

Why did my zip code lose its leading zero?

Type inference turned the text 07030 into the number 7030. Tablizer leaves inference off by default for exactly this reason, and refuses to convert any value starting with a zero followed by a digit even when it is on.

Is there a limit on file size?

No. The work happens on your own machine, so the limit is your machine's memory rather than an upload cap. A file with tens of thousands of rows converts in a second or two.

Is my data uploaded anywhere?

No. The parsing and generating are done by JavaScript running on this page. You can watch the network tab while you convert and see that nothing is sent.

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