Online Tool Store
Duplicate Column Detector
Paste a CSV header row to catch exact duplicate column names and near-duplicates like "Email" vs "E-mail" before an import or join breaks.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Duplicate column detector
Paste a CSV header row (or the whole file) to catch duplicate or near-duplicate column names.
Exact duplicates (0)
Near-duplicates (0)
All columns (0)
How it works
- Paste your CSV data — only the first row (the header) is read.
- Each column name is compared exactly (trimmed, case-insensitive) and loosely (punctuation and spacing ignored too).
- Exact and near-duplicate groups are listed separately, so you can tell a true duplicate from a likely rename.
FAQ
What counts as an exact duplicate?
Two column names that are identical once trimmed and lowercased — so "Email" and "email" are flagged as exact duplicates, but "Email" and "E-mail" are not.
What counts as a near-duplicate?
Column names that match once whitespace and punctuation are stripped too — so "E-mail", "e mail", and "Email" are flagged as near-duplicates of each other, since they likely refer to the same field spelled differently.
Does this run in my browser?
Yes. The header row is parsed and compared locally in the page — nothing is uploaded or sent to a server.
Can I save the output?
Yes. The download button saves a plain-text report listing the exact and near-duplicate groups found.
How we compare
| Feature | Online Tool Store | Manual spreadsheet review | Eyeballing the header row |
|---|---|---|---|
| Flags near-duplicates (e.g. "Email" vs "E-mail") | Included | Requires a formula | Easy to miss |
| Instant results as you type | Included | Manual refresh | N/A |
| Private, local workflow | Yes | Depends on setup | Yes |
Use this before a database import or a join, where a duplicate or inconsistently-named column silently breaks the result.