# CSV to Excel (.xlsx)

Convert CSV, TSV or JSON into a real Excel .xlsx workbook — typed number/boolean columns, a bold frozen header, auto-fit widths. In-browser, nothing uploaded.

## Run it

- **CLI:** `gizza tool csv-to-xlsx "name,age,active
Alice,30,true
Bob,25,false"`
- **Web:** https://gizza.ai/tools/csv-to-xlsx/

## Inputs

- `data` — Table data (CSV / TSV / JSON) _(field)_
- `input_format` — Source format _(field)_
- `sheet_name` — Sheet name _(field)_
- `header` — First row is a header (bold + frozen) _(field)_
- `detect_types` — Detect number & boolean types _(field)_
- `autofit` — Auto-fit column widths _(field)_

## Output

- Workbook (text)

## Query parameters

Open the tool pre-filled and auto-run via URL:

- `data` — Table data (CSV / TSV / JSON)
- `input_format` — Source format
- `sheet_name` — Sheet name
- `header` — First row is a header (bold + frozen)
- `detect_types` — Detect number & boolean types
- `autofit` — Auto-fit column widths

Example: `https://gizza.ai/tools/csv-to-xlsx/?data=name%2Cage%2Cactive%0AAlice%2C30%2Ctrue%0ABob%2C25%2Cfalse&input_format=auto&sheet_name=Sheet1&header=true&detect_types=true&autofit=true`

---

## Turn a CSV, TSV or JSON table into a real Excel workbook

Paste your table, pick the source format (or leave it on **Auto-detect**), and download a genuine
binary `.xlsx` file — the same format Excel, Google Sheets, LibreOffice and Numbers open natively.
This is a real workbook, not a renamed CSV: numbers are written as **native number cells**, `true` /
`false` become **boolean cells**, the first row can be a **bold, frozen header**, and each column is
**auto-sized** to its content. Everything runs in your browser with WebAssembly — your data is never
uploaded to a server.

### Worked example

Input (CSV, with "Detect number & boolean types" on):

```
name,age,active
Alice,30,true
Bob,25,false
```

Output: a `People.xlsx` workbook whose first sheet has a bold, frozen header row
(`name` · `age` · `active`), then two data rows. In the resulting spreadsheet the **age** column
holds real numbers (`30`, `25`) you can sum or sort, and the **active** column holds real booleans —
not the text `"30"` or `"true"`. Set the **Sheet name** field to name the worksheet tab (it also
becomes the download's filename).

JSON works too — paste a JSON array of objects and the keys become the columns:

```
[{"product":"Widget","qty":12,"price":9.99},{"product":"Gadget","qty":3,"price":19.5}]
```

## FAQ

<details>
<summary>Is this a real .xlsx file, or just a CSV renamed to .xlsx?</summary>

It is a real, standards-compliant Office Open XML (`.xlsx`) workbook — a ZIP of XML parts, exactly
what Excel writes. It opens without the "the file format doesn't match the extension" warning you get
from a renamed CSV, and it carries native cell types (numbers, booleans) plus formatting like the
bold, frozen header row.

</details>

<details>
<summary>Do numbers stay numeric, and are leading zeros preserved?</summary>

With **Detect number & boolean types** on (the default), delimited cells that look like whole numbers
or decimals become native number cells, and `true` / `false` become booleans — so totals, sorts and
charts work. Values with a leading zero (`007`), a leading `+`, or underscores stay **text**, so zip
codes and phone numbers aren't mangled. Turn the option off to force **every** delimited cell to text.
JSON and NDJSON keep whatever types they already declare.

</details>

<details>
<summary>Which input formats and delimiters are supported?</summary>

CSV (comma), TSV (tab), semicolon-separated, and pipe-separated delimited text, plus a JSON array of
objects/rows and NDJSON (one JSON value per line, a.k.a. JSONL). **Auto-detect** sniffs the format
from your text, picking the most frequent of comma / tab / semicolon / pipe on the first row (or JSON
when the text starts with `[` or `{`). Pick a specific format from the dropdown to override the guess.

</details>

<details>
<summary>How are the columns and the header row decided?</summary>

For delimited input with **First row is a header** on, the header cells become the bold, frozen top
row. For a JSON array of objects the column set is the **union of all keys** in first-seen order, so
rows with different fields still line up (missing values are left blank). Turn the header option off to
write only data rows with no header.

</details>

<details>
<summary>Are there any size or shape limits?</summary>

A worksheet can hold at most 1,048,576 rows and 16,384 columns (Excel's own limits) — going over
returns a clear error. The workbook is capped at 24 MB. Nested JSON values (arrays/objects inside a
cell) are written as their compact JSON text so nothing is silently dropped. Everything is computed
locally in your browser, so very large pastes are bounded by your device's memory.

</details>