Tablizer

Convert JSON Lines to Markdown Online

Paste a JSON Lines table below, edit it if you need to, and get Markdown 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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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 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 Markdown is

A Markdown table is rows of pipe-separated cells with a dashed rule under the header. Alignment is set by placing colons in that rule.

README files, GitHub issues, documentation sites, Obsidian and Notion.

What changes when you convert JSON Lines to Markdown

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.

Cells are padded so the source lines up in a plain text editor, pipes inside values are escaped, and line breaks inside a cell become <br> because a Markdown table row cannot span lines.

What carries over from JSON Lines to Markdown

JSON Lines records 3 things about a table that Markdown has no way to hold.

JSON Lines distinguishes a number from the text of a number; Markdown does not, so every value arrives as text and has to be re-parsed by whatever reads it next.

An empty cell and a missing one are the same thing in Markdown, so a null and an empty string in the JSON Lines both come out blank and can no longer be told apart.

JSON Lines can hold a value that is itself a list or an object. Markdown has only flat cells, so nested values are flattened into one cell rather than being spread across columns.

Markdown marks header cells differently from data cells, so the keys are lifted out and written once as a marked header row rather than repeated on every row.

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

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

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"}
Markdown out
| id  | name             | role          | started    | hours |
| --- | ---------------- | ------------- | ---------- | ----- |
| 007 | Halima Yusuf     | Analyst, data | 2024-03-15 | 38.5  |
| 012 | Jonah "Jo" Pryce | Engineer      | 2025-11-02 |       |
| 104 | Wei Chen         | Manager       | 2023-06-30 | 40    |

Questions

How do I convert JSON Lines to Markdown?

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 Markdown 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.

Can a Markdown table cell contain a line break?

Not directly. The row ends at the newline. Use a <br> tag inside the cell, which every common Markdown renderer passes through to the HTML output.

Will my numbers still be numbers?

They will read the same, but Markdown stores them as text. Anything that sorts or sums the result will need to parse them first, and a leading zero or a currency symbol is the usual place that goes wrong.

What happens to nested values?

Markdown has no nested cell, so a list or object inside a JSON Lines value is flattened into a single cell rather than expanded into extra columns. Split it before converting if the parts need to be separate.

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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