Forward-fill blank cells from the value above in a CSV column
Forward-fill blank cells by propagating the last non-blank value down through a CSV column.
🛡️ Your rows never leave your browser.
Why Onfyt: Detects fill-down candidates automatically using statistical heuristics (columns with long blank runs between values) and pre-selects them—no manual column selection needed.
Interactive Sample Data
| region | category | product | revenue |
|---|---|---|---|
| Nairobi | Solar | Panel 250W | 4500 |
| Panel 300W | 5200 | ||
| Battery | Lithium 100Ah | 3800 |
How this tool works
Forward-fill (also called fill-down or ffill) is the most common operation for correcting CSV files exported from Excel workbooks with merged cells, or data systems that only write a group-header value on the first row of each group. Without fill-down, GROUP BY operations on the 'region' column produce wrong results because subsequent rows have blank regions.
DataFix's fill-down applies to the selected columns: for each blank cell, the tool writes the most recent non-blank value in that column above it. Fills stop at the next non-blank value or at file end.
Reports formatted for visual reading often leave repeated category cells blank beneath the first entry. When exported to CSV, these blank cells break database queries that group by category. DataFix fills down the last seen non-empty value into consecutive blank cells, restoring complete relational integrity across every row.
Filling down non-empty values into succeeding blank cells resolves sparse reporting tables, ensuring that every observation carries its full hierarchical parent categorization.
Populating blank reporting cells with the last preceding value resolves sparse tables exported from visual spreadsheets. Restoring full category labels to every row enables accurate relational database queries. Directional fill controls also support filling upward or across row axes, accommodating diverse historical report formatting conventions and multi-tier tables.
Things that usually go wrong
- If the first row in a column is blank, there is no value to fill down from — those cells remain blank.
- Fill-down only moves downward; it does not fill blank cells at the top of a column.
Edge cases we tested
🧪 First row of column is blank
No value to propagate from; blank preserved with a warning.
🧪 Entire column is blank
No change; flagged as candidate for column removal.
Frequently Asked Questions
What is fill-down used for?
Spreadsheet exports of merged cells often leave only the first row filled. Fill-down restores the repeated value to every row in the group.
Can I fill multiple columns at once?
Yes. Select all columns that need filling before running the tool.
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