CSV Import Preflight Guide: Encoding, Columns, Keys, and Validation

A failed import is often caused by a small mismatch: the wrong encoding, a missing header, a duplicate identifier, or a file that is simply too large for the destination. This guide turns those checks into a short, repeatable sequence.

1. Confirm the source encoding and dialect

Start with CSV Encoding Fixer when accents or non-Latin product names look garbled. The CSV Dialect & Encoding Matrix provides synthetic fixtures for UTF-8, BOM, Windows-1252, ISO-8859-1, GBK, Shift_JIS, delimiters, and line endings. Keep the original file unchanged until the decoded preview looks correct.

2. Align the target headers

Use CSV Column Mapper to rename, reorder, or omit columns deterministically. Mapping changes headers and order only; it does not transform cell values or prove that a marketplace schema is complete.

3. Check identifier quality

Run Duplicate SKU Checker before an update or merge. A stable unique key such as SKU, product ID, EAN, or Handle should identify one row in the source. Blank keys and case differences need an explicit decision rather than silent deduplication.

4. Validate required values

Use CSV Validator to check required headers, blank required cells, blank keys, and duplicate non-blank keys. For a current WooCommerce product import, use the narrower WooCommerce CSV Checker, then read the official importer documentation and test a small file on staging.

5. Compare before and after exports

When a supplier or catalog export changed, Catalog CSV Diff matches rows by a shared key and reports added, removed, and changed cells. Fix duplicate or blank keys first; comparing row numbers creates noise when a system reorders products.

6. Batch only after the file is clean

Use CSV Splitter after validation when the destination has row, size, or grouping limits. Every part repeats the header, but the tool is still browser-memory bound and is not a streaming large-file service.

A safe preflight sequence

1. 1

   Keep an untouched source copy and remove credentials or personal data from any reproduction.

2. 2

   Confirm encoding, delimiter, line endings, and header names.

3. 3

   Check stable keys, required values, and destination-specific rules.

4. 4

   Compare changes, split the validated file if needed, and test a small batch on staging.

Boundary: A clean report means only that the declared checks passed. Plugins, themes, server limits, remote images, custom fields, and destination configuration can still change import behavior.