How to review a large event registration CSV

Your event registration export has thousands of rows, and checking names, email addresses, ticket types, and payment notes one by one is slow. A quick review can catch missing details and repeated registrations before you use the list for check-in or follow-up.

Open the file in the CSV Editor to find values, sort columns, edit cells, and remove duplicate rows in your browser. Keep an untouched copy of the original so you can undo a mistake.

Review the registration CSV

1. Open the CSV Editor and open a copy of your registration export. The editor can handle CSV files with up to 10 million rows, though very large files may take longer or use substantial browser memory.
2. Check the column headings and a few rows near the top. Confirm that names, email addresses, ticket types, and any other important fields appear in separate columns, and that the text is readable.
3. Use the find feature to look for values you expect to be present, such as a particular ticket type, event date, or email domain. Search for a few known attendees to confirm the data is in the file.
4. Sort important columns, such as email address, ticket type, or registration date. Look for blank cells, unusual values, repeated addresses, and entries that do not fit the event's expected format.
5. Make corrections only after checking them against your registration records. Use duplicate removal only when you know which rows count as duplicates, then save or download the reviewed file as a new copy.

If the CSV is too large to inspect comfortably, you can also use the large-file review approach to narrow down what needs attention before making changes.

What the results mean

Columns and values look consistent

If each value is under the expected heading and searches find the attendees you expect, the file is probably structured well enough to continue reviewing. This does not confirm that every registration is valid, but it rules out some common export and formatting problems.

Some cells are blank

A blank cell could mean the attendee skipped an optional question, the form allowed an incomplete answer, or the export lost a value. Sort the relevant column to bring blanks together, then check whether the field was required before deciding to contact anyone.

Several rows share an email address

This may be a duplicate registration, but it can also be a family member registering multiple people, a shared work address, or a person with separate tickets. Compare names, registration times, order numbers, and ticket details before removing anything. Matching email addresses alone are not proof of a duplicate.

A value appears in the wrong column

Check whether the row contains commas, quotation marks, or line breaks that were not handled correctly in the export. If many rows shift in the same way, the problem may be the CSV format or delimiter rather than individual registrations. Avoid editing the affected cells until you understand the pattern.

How to fix common CSV problems

1. Keep the original unchanged. Make a working copy before sorting, editing, or removing rows. This gives you a way back if you delete a valid registration or change a value by mistake.
2. Check the export settings. If columns appear misaligned, export the registrations again from the source system and use its standard CSV option. When asked about a separator, choose the one used by the file, usually a comma. Opening the file again with the correct separator may restore the columns.
3. Use sorting to group incomplete entries. Sort a required field, such as email or ticket type, so blank or unusual values are easier to spot together. Check each row against the original registration record before filling in missing information.
4. Review possible duplicates before removing them. Compare more than one field, such as name and order number. If the editor's duplicate-removal option does not let you define which columns determine a match, do not use it on the full registration list unless whole-row matches are exactly what you want removed.
5. Check date and number formats. A date such as 04/05/2025 can mean different things in different regions. Confirm the intended date format with the event organizer before changing it. Treat registration IDs and postal codes as text when leading zeros matter.
6. Save a separate reviewed copy. Give the new file a clear name, such as event-registrations-reviewed.csv, and reopen it to check that your changes were preserved. Keep access to the original restricted if it contains attendee details.

Be careful with duplicate removal

Two rows can look similar without representing the same person or order. For example, one attendee may register twice by mistake, while a coordinator may intentionally submit several registrations using one email address. A safe rule is to identify duplicates using the event's own unique order or registration ID, if available, and confirm the rows before deleting them.

Do not treat a repeated name as a reliable match. Names can be shared, misspelled, or entered differently, and a single person may have multiple tickets. If you are unsure, mark the records for follow-up instead of removing them from the working list.

Protect attendee information

Registration files may contain names, email addresses, phone numbers, or accessibility requests. The CSV Editor runs in your browser, and the file stays on your device. Still, avoid leaving the file open on a shared computer, and do not send an edited attendee list to people who do not need it.