Tablizer

Convert JSON Lines to JPEG Online

Paste a JSON Lines table below, edit it if you need to, and get JPEG 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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Paste or upload something above and it will appear here.
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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 JPEG is

A lossy image format designed for photographs, where losing a little detail in a gradient is invisible.

Places that will not accept a PNG upload.

What changes when you convert JSON Lines to JPEG

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.

The same render as PNG, saved as JPEG. It is the worse choice for a table and it is worth knowing why: JPEG compresses by discarding detail around sharp edges, and a table is nothing but sharp edges. Letters get a visible halo and hairline rules blur. It also has no transparency, so a background colour is always painted rather than left clear.

What carries over from JSON Lines to JPEG

JSON Lines records 5 things about a table that JPEG has no way to hold.

JSON Lines knows which of its values are numbers. JPEG keeps only their appearance, so nothing downstream can sort or sum them without someone reading them back off the image first.

An empty cell and a missing one are the same thing in JPEG, 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. JPEG has only flat cells, so nested values are flattened into one cell rather than being spread across columns.

JSON Lines can be read one record at a time. JPEG 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.

JPEG is the end of the line for this data. Reading the table back out of it is a separate and much harder problem than writing it, so keep the JSON Lines if you will need the values again.

Questions

How do I convert JSON Lines to JPEG?

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 JPEG 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.

Should I use JPEG or PNG for a table?

PNG, unless something you are uploading to refuses it. JPEG was designed for photographs and its compression damages exactly the kind of high-contrast edges that text and table rules are made of.

Can I convert the JPEG back to JSON Lines afterwards?

Not mechanically. JPEG keeps how the table looks, not what it held, so going back means reading the values off the page again. Keep the JSON Lines if you will need it.

Will my numbers still be numbers?

They will look the same, but JPEG holds no values at all - only their appearance. Nothing can add up a column of a JPEG without the numbers being read back out of it first.

What happens to nested values?

JPEG 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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