Tablizer

Convert JSON Lines to YAML Online

Paste a JSON Lines table below, edit it if you need to, and get YAML back. The conversion runs in your browser, so nothing is uploaded, there is no size limit and there is no signup.

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What JSON Lines is

JSON Lines is one complete JSON object per line, with no enclosing array and no commas between records. The file is not valid JSON as a whole, and that is the point.

Log pipelines, machine learning datasets and anything that appends records or reads them in a stream.

What YAML 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 changes when you convert JSON Lines to YAML

Each line is parsed on its own, so a corrupt record does not take the file with it. Keys are unioned across lines in first-seen order, so a record missing a field leaves that cell empty rather than shifting the columns.

You get a list of maps, one per row, with long lines left unwrapped so values do not get folded across lines.

What carries over from JSON Lines to YAML

One property of the JSON Lines has no home in YAML, and it is worth knowing which before you convert.

JSON Lines can be read one record at a time. YAML has to be complete before it means anything, so the whole table is held in memory while it is written and a file that gets cut off part way through is not partly usable - it is unusable.

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

The identifier 007 comes out of the YAML 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 YAML file goes wrong.

The quotes around Jonah "Jo" Pryce are left as a plain quote character in the YAML.

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.

JSON Lines 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"}
YAML out
- 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 JSON Lines to YAML?

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

What is the difference between JSON and JSON Lines?

JSON wraps records in an array, so a reader must load the whole document before it can use any of it, and appending means rewriting the file. JSON Lines has no wrapper, so records can be streamed and appended one at a time. Use JSON for a payload, JSON Lines for a log.

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.

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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