Tablizer

Convert Markdown to JSON Lines Online

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

From

The only part of this site that uses a server. The address is sent to it so the page can be fetched, because a browser is not allowed to fetch someone else's page itself. Your own files are never involved.

Nothing here is uploaded. The parsing happens on this page.
Edit
Paste or upload something above and it will appear here.
ToDataMarkupDocumentsCodeSchemasImages

The output will appear here once there is a table to convert.

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 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 changes when you convert Markdown to JSON Lines

Leading and trailing pipes are optional and both are handled. A pipe the author escaped with a backslash is read as data rather than a column break, which is the usual reason a hand-written table parses one column too wide.

Every row becomes one line. You can append to the file forever without rewriting it, and a reader can process it a line at a time without holding the whole thing in memory.

What carries over from Markdown to JSON Lines

Markdown records 2 things about a table that JSON Lines has no way to hold.

JSON Lines wants a type for each column, and Markdown does not record one, so each column is typed from what its values look like. A column of digits that should stay text - a zip code, a phone number, a leading-zero id - is the usual thing to check afterwards.

JSON Lines has no header row. The column names are repeated as keys on every record instead, which is why the result is bigger on disk than the table it came from.

Anything visual in the Markdown - weight, alignment, colour, column widths - has no counterpart in JSON Lines and is dropped. The values are what survives.

The identifier 007 comes out of the JSON Lines 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 Lines file goes wrong.

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

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.

Markdown in
| 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    |
JSON Lines 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 Markdown to JSON Lines?

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

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.

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.

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.

Related conversions