Tablizer

Convert Markdown to Avro Schema Online

Paste a Markdown table below, edit it if you need to, and get Avro Schema 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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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.
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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 Avro Schema is

An Avro schema describes a record: its name and its typed fields. It is the contract, not the data.

Kafka pipelines and anything in the Hadoop family.

What changes when you convert Markdown to Avro Schema

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.

Types are inferred per column from the values present. Any column with a gap in it becomes a union with null, because a reader rejects a record whose non-nullable field is missing.

What carries over from Markdown to Avro Schema

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

Avro 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.

Avro 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 Avro and is dropped. The values are what survives.

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    |
Avro Schema out
{
  "type": "record",
  "name": "staff",
  "fields": [
    {
      "name": "id",
      "type": "long"
    },
    {
      "name": "name",
      "type": "string"
    },
    {
      "name": "role",
      "type": "string"
    },
    {
      "name": "started",
      "type": "string"
    },
    {
      "name": "hours",
      "type": [
        "null",
        "double"
      ]
    }
  ]
}

Questions

How do I convert Markdown to Avro Schema?

Paste your Markdown into the box above or drop the file onto it. Check the table in the grid, then copy or download the Avro Schema 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.

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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