Tablizer

Convert TSV to JSON Online

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

TSV is CSV with tabs instead of commas. Because tabs almost never appear inside a value, quoting is rarely needed and the files are easier to read by eye.

Bioinformatics, log processing, and anyone who has copied a block of cells out of a spreadsheet: the clipboard format is TSV.

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 TSV to JSON

The tab is unambiguous, so there is no delimiter to guess. This is the most reliable of the delimited formats to read.

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.

What carries over from TSV to JSON

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

JSON wants a type for each column, and TSV 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 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.

TSV can be read one record at a time. JSON 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.

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.

TSV 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 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 TSV to JSON?

Paste your TSV 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 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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