Remove exact duplicate records and review likely matches.
Choose what makes a record identical, preview which rows remain, and export a separate CSV. Exact rules can remove duplicates. Similarity scores remain suggestions for a person to assess.
1. Choose a CSV to review duplicates
Your file opens directly in the local app. Contents stay in this browser; no account needed.
Up to 20 MiB, 100,000 rows and 500 columns.
- Choose CSV
- Review possible matches; choose exact duplicate rules
- Review and download a new CSV
Possible matches are suggestions. They are never deleted automatically.
Deduplicate complete rows
Use exact-row deduplication when every field must match. The first record in source order is preserved, so the result follows a predictable rule instead of choosing a winner silently.
Deduplicate by a business key
Select stable columns such as a customer ID or an approved combination of identifiers. Selected-key deduplication compares only those values, which keeps the decision explicit and repeatable.
Treat fuzzy matches as evidence
Spelling differences and similar names can indicate duplicates, but they can also identify different people or companies. Fuzzy results show pairs and scores without modifying the file.
Check the result before export
Review the row count and preview after each deduplication step. Undo a step if the key was too broad, then download a new CSV without overwriting the source.
Frequently asked questions
How does exact record deduplication choose the row to keep?
It preserves the first record in source order. Match every field or choose approved key columns, then review the result before exporting.
Are similar names automatically merged or deleted?
No. Fuzzy matches show candidate pairs and scores for review. They do not modify the CSV or establish that two records represent the same person or company.
Is my CSV uploaded when I clean it locally?
No. Local cleaning processes the CSV in this browser without an account. Temporary Loam mode is a separate option and uploads a copy only after you confirm it in the application.
Which files can I clean?
Local mode accepts one CSV up to 20 MiB, 100,000 rows and 500 columns. Export other formats as CSV first. Download your cleaned result before refreshing or closing the tab.
Does cleaning overwrite my original CSV?
No. Rules change a preview that you can undo or reset. Export downloads a separate cleaned CSV and processes the complete accepted file.