Why opening a CSV in Excel goes wrong
Double-clicking a CSV file often gives you a mess: everything in one column, accented letters turned into strange symbols, or zip codes and account numbers that lost their leading zeros. Long numbers such as card or ID numbers can turn into scientific notation and lose their last digits.
This converter reads the CSV first, detects whether the separator is a comma, a semicolon or a tab, and writes a real Excel .xlsx file. Numbers stay as numbers so you can add them up, but codes with leading zeros and numbers longer than 15 digits are kept as text, exactly as they were. That covers zip codes, product codes, ID numbers and bank account numbers.
Formats it reads and writes
It reads CSV and TSV; JSON, as an array of objects, where nested objects are flattened into columns such as address.city; XML, where it detects the element that repeats and turns each one into a row, with its children and attributes as columns; and Excel .xlsx files, all sheets, using the stored values. It does not read the old .xls format; open it in a spreadsheet program and save it as .xlsx first.
It writes Excel .xlsx, CSV with a comma, semicolon or tab, and JSON. For CSV there is an Excel-compatible option that keeps accents and special letters readable when the file is opened in Excel.
Everyday uses
Bank statements, online store orders, email lists and reports from accounting or payroll systems are often exported as CSV; converting them gives you a spreadsheet you can sort, filter and share. Developers and analysts get JSON from APIs and need a table for a colleague who works in Excel. Invoices, product feeds and reports in XML become readable rows. And when a system asks you to import a CSV, Excel to CSV produces it from your spreadsheet.
You can convert several files at once, and the preview shows the first rows so you can confirm the columns look right before downloading.
Private by design
Data files often contain customer names, amounts and account numbers. Here the conversion happens in your browser, so the file is not uploaded to any server and nothing is stored. It is free, without an account and without limits beyond your device's memory. There are shortcut pages for each case: Excel to CSV, JSON to CSV, JSON to Excel, CSV to JSON and XML to Excel. To edit the result online, Online spreadsheet opens .xlsx and .csv files.