Extract the first or last N rows from a CSV file
Extract the first N or last N data rows from a CSV file, preserving the header.
🛡️ Your rows never leave your browser.
Why Onfyt: CSV-aware head/tail that won't split quoted multi-line cells the way shell commands do—handles embedded newlines correctly.
Interactive Sample Data
| id | event | timestamp |
|---|---|---|
| 1 | login | 2024-01-01T08:00:00Z |
| 2 | purchase | 2024-01-01T09:15:00Z |
| 3 | logout | 2024-01-01T10:30:00Z |
How this tool works
When debugging a pipeline issue on a million-row log file, engineers routinely reach for shell commands like `head -n 100 file.csv` or `tail -n 50 file.csv`. DataFix brings this capability to the browser with proper CSV-aware parsing—unlike shell head/tail, this tool handles multi-line quoted cells without splitting them incorrectly.
Common use cases: preview the structure of a large file without opening it in Excel, extract the most recent 50 audit events from the end of a log CSV, or create a small test fixture from a production dataset's first 200 rows.
Truncating files to a specific row count is essential for preview generation, baseline data testing, or extracting recent transaction logs. DataFix lets you keep the top N rows (head) or bottom N rows (tail) of any spreadsheet or CSV, retaining the header row and preserving row structures with instant client-side execution.
Extracting top-N or bottom-N rows provides fast sample verification and test harness creation, allowing developers to test ETL scripts against valid header-aligned extracts without processing complete production volumes.
Extracting top or bottom record slices allows engineers to inspect export formats, verify header alignment, and generate lightweight test fixtures. Truncating datasets to specific row counts executes instantaneously without corrupting trailing line delimiters. Boundary checks ensure that requesting more rows than exist in the file returns the entire dataset gracefully without index out-of-range exceptions.
Things that usually go wrong
- If N exceeds the number of rows, all rows are returned without error.
- The header row is always preserved and is not counted in N.
Edge cases we tested
🧪 N larger than total row count
Returns all available rows with a warning.
🧪 Last N with multi-line quoted cells
Cells with embedded newlines counted as one row, not multiple.
🧪 Skip first 500 rows on a 490-row file
Returns header only; warning issued.
Frequently Asked Questions
Can I keep a random sample instead?
Use the Pick Random Sample Rows tool for random sampling.
Can I keep rows from the middle of the file?
Use the Filter CSV Rows by Condition tool with a row-number condition.
Related tools
Reshape
Transpose CSV
Flip a CSV matrix by turning rows into columns and columns into rows.
Open Tool →
Reshape
Pivot a CSV
Summarise long-format CSV data into pivot tables grouped by row and column keys.
Open Tool →
Reshape
Group By and Count
Aggregate CSV rows by one or more group-by columns with count, sum, mean, min, or max.
Open Tool →