Open large CSV files without Excel
Excel stops at 1,048,576 rows, is slow with big files, and changes data as it opens it: long IDs turn into scientific notation, leading zeros vanish from codes and phone numbers, and some text is read as dates. This viewer shows every value exactly as it is in the file, and its table only draws the rows on screen, so files with hundreds of thousands of rows scroll smoothly.
- Formats: CSV and TSV (the delimiter is detected: comma, semicolon, tab or pipe), Excel
.xlsx,.xlsand.odswith a sheet picker, and JSON arrays or NDJSON. Nested JSON fields are flattened into columns such asaddress.city. - Sort by clicking a column header: numbers sort as numbers, text alphabetically, and empty values go last.
- Filter to rows that contain all the words you type, across every column.
- Export the filtered, sorted rows as CSV, JSON or Excel.
What the column profile tells you
Before you analyse or import a dataset, it pays to check its quality. The Profile tab summarises every column:
| Measure | Why it matters |
|---|---|
| Detected type | Integer, decimal, date, boolean, email, URL or text. A column you expect to be numeric but which shows as text usually contains a stray value such as N/A. |
| Empty values | Missing data, flagged when more than a fifth of a column is empty. |
| Distinct values | Whether a column could be a key (every value unique) or is a category with a few repeated values. |
| Min, max, mean, median, standard deviation, sum | Spots outliers and impossible values, such as negative quantities or prices of 0. |
| Distribution | A small histogram of each numeric column. |
| Most common values | Reveals inconsistent spellings ("NY", "New York", "new york") and placeholder values. |
| Warnings | Mixed numbers and text, and values with leading or trailing spaces that break joins and lookups. |
Click a profile card to jump back to the table sorted by that column.
Private by design
Your file is read by your browser and never uploaded, so it's safe for customer lists, finance exports and other confidential data. Nothing is stored after you close the tab. When you want to go further, Query with SQL opens the same data in the SQL tool.
Frequently asked questions
How do I open a large CSV file?
Drop it on this page. The viewer reads the file in your browser and only draws the rows on screen, so files with hundreds of thousands of rows stay fast. Files up to 300 MB can be opened; for larger ones, use the SQL tool, which reads files without loading them fully into memory.
Can it open Excel files?
Yes: .xlsx, .xlsm, .xls and .ods. If the workbook has several sheets, pick one from the Sheet menu. Dates are shown as ISO dates (2026-10-03) and numbers without Excel formatting.
Why do my numbers look different from Excel?
Excel applies display formats such as thousands separators, currency symbols and rounding. The viewer shows the underlying value, which is what other systems will receive when you export or import the data.
What does data profiling mean?
Summarising each column to understand its content and quality: its type, how many values are missing or distinct, the range of values and the most frequent ones. It is usually the first step of any data analysis or migration.
Is my data uploaded?
No. Files are read and profiled in your browser and never sent to a server.