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From three files to a deliberate decision.

For event administrators combining invitation batches. This free offline demo checks a narrow preparation step, not a completed platform import.

Choose + mapReview each rowApproved CSV→→

Try the included synthetic pack

  1. Open index.html locally in a modern desktop browser. Choose fixtures/current-roster.csv as reference, then incoming-a.csv and incoming-b.csv.
  2. Confirm the three mappings. Click Review mapped files. Expect 10 rows per file, 30 total. Review raw values through each row's disclosure.
  3. There are three match rows, one name conflict and five invalid/blank incoming rows. Review these rather than merging. Same-name/different-email is informational.
  4. For the documented control, include only clear and same-name rows; exclude the other incoming rows with a reason. Reference rows need no decision.
  5. Acknowledge the omissions/safety transformations, then export. Expect 11 candidate records. Download the review log separately; it contains raw input data and decisions, so keep it private.

Rules and limits

At most one reference and two incoming UTF-8 CSVs; 1 MB per file and 5,000 combined data rows. Duplicate/blank headers, mismatched column counts, malformed quotes and unsupported UTF-8 stop review. Choose distinct mappings. Extra columns remain visible in raw review but are omitted from export.

Trimmed, case-insensitive email matching is a disclosed heuristic, not proof of identity. Shared email requires review; differing names on that email cannot be included. Blank required fields and limited email-shape failures block inclusion. Same-name/different-email never merges. All incoming decisions require a reason. Exports trim mapped values, quote fields and prefix cells starting with = + - @ with an apostrophe; review these transformations before use. Leading zeros and Unicode remain text.

Use corrected-a.csv and corrected-b.csv to confirm the four repaired required-field exceptions clear while the other batch's blank first name remains blocked. No automatic edits to originals, overwrite, persistence or network requests. Reset clears this utility's state; your original and downloaded files are not deleted. Local browser extensions and the operating system remain outside this demo's control.

What this does not prove

No email deliverability, attendee consent, identity resolution, custom-field migration, verified native import, physical testing, spreadsheet speed advantage or buyer demand is claimed. The separate spreadsheet baseline describes operations, not a measured human study. AI-assisted original code; no EventCreate affiliation. Paid checkout is closed; the possible $19 utility price is unvalidated.

After export, manually map and inspect the destination's preview. Do not import without permission to contact those people. Never email us attendee files.