Open Excel files online in a browser tab
Someone emails you an .xlsx with a budget, a price list or a class roster, and you are on a laptop or phone without a spreadsheet program. This free online spreadsheet opens Excel .xlsx files and CSV exports right in your browser, so you can read them, fix a number and send them back. It is an independent tool, not Microsoft Excel, but it reads and writes the same .xlsx format.
When you open an .xlsx, the values and formulas from every sheet are loaded, and each sheet appears as its own tab. You can edit any cell, add or delete rows and columns, and create new sheets for extra data.
Formulas that do the math for you
Type a formula that starts with an equals sign and the cell calculates the result. The common functions are there: =SUM, =AVERAGE, =IF, =COUNT, =MIN, =MAX, =ROUND and =CONCATENATE, among others. That covers most household and office sheets: adding up expenses, averaging grades, flagging overdue invoices with an IF, or joining first and last names into one column.
If you learned spreadsheets in Spanish or Portuguese, the most common function names in those languages work too, such as SUMA or SOMA, PROMEDIO or MÉDIA, SI or SE, CONTAR, REDONDEAR, and HOY or HOJE. Files shared across teams in different countries open without rewriting every formula.
What is kept and what is not
This tool focuses on data and calculations. When you save as .xlsx, both values and formulas go into the file, so it opens with working formulas in other spreadsheet programs. Saving as .csv exports only the active sheet, which is the format many banks, stores and online forms ask for when you import data.
Formatting is a different story. Colors, borders, number formats, charts, filters and merged cells are not kept when you open an .xlsx. If your file is a polished report full of charts and styling, use a full desktop program for it. For lists, budgets, inventories and quick calculations, the data comes through intact.
Everyday uses
A shop owner can update stock counts from a phone between customers. A teacher can open a gradebook exported as CSV, add a column for the final exam and average it. A freelancer can total the hours on a timesheet a client sent and return the corrected .xlsx. A family can keep a shared monthly budget in one file and pass it around by email.
When you need the sheet as a PDF, download the .xlsx and use “Save as PDF” in Excel, LibreOffice or Google Sheets.
Private and free
The spreadsheet runs in your browser, so your file never leaves your device and nothing is stored on our side. There is no cloud copy either: the sheet lives in the tab until you download it, so save before closing. ConvertirDocs is 100% free, with no sign-up, no usage limits and no paid tier.