Missing Values Detector

Missing Values Detector is a free online tool that works entirely in your browser — no signup, no data uploaded, no limits.

Missing Data Hides Until It Breaks Something

A spreadsheet looks complete when you skim it. Then a report generation script crashes on row 340 because a required field is blank, or a calculation silently treats a missing number as zero and produces a wrong total. Missing values rarely announce themselves — they just sit quietly until something downstream depends on them.

This tool scans every cell in your CSV and checks not just for genuinely empty strings but also for common placeholder values like NULL, N/A, and a lone dash, since these represent the same underlying gap even though the cell technically contains text. The output shows exactly which rows and which columns have a problem.

Why Row-Level Detail Matters More Than a Summary Percentage

Knowing a column is 85% complete tells you there is an issue. Knowing specifically that rows 12, 47, and 203 are missing the phone number tells you exactly what to fix and lets you investigate whether those rows share something in common — maybe they all came from a particular import batch that had a problem.

Distinguishing Optional Fields From Required Ones

Not every missing value is a problem. A middle name field, a secondary phone number, or an optional notes column being blank is normal and expected. The tool reports every gap it finds, but deciding which gaps actually matter for your use case requires knowing which fields in your specific dataset are supposed to always be filled.