Check one CSV before import
Use this when you have one CSV and want to find issues before Excel, Shopify, HubSpot, Mailchimp, or another system changes it.
Files stay in your browser. No upload. No account. No storage.
Fix and precheck messy CSV files before Excel or imports change your data
Upload a broken CSV, preview what went wrong, and download a clean UTF-8 file. Argon can also flag common Excel and import-readiness risks, or compare two CSV files before import or update.
Files stay in your browser.
Instant processing
Checks for encoding, delimiter, and wrapped-row issues.
Choose the right CSV tool
What are you trying to do?
Files stay in your browser. No upload. No account. No storage.
Compare two CSV files
Use this when you have an old file and a new file and want to see added, removed, duplicate, blank-key, or changed rows.
Fix a CSV that opens wrong in Excel
Use this when everything opens in one column, characters look weird, or product codes changed.
Check a Shopify / product CSV
Use this for product files, supplier files, SKUs, handles, variants, or catalog updates.
Check a contact / email list
Use this before importing contact lists into CRM or email tools.
Not sure? Start with CSV Precheck. It inspects the file locally and shows review items.
CSV Precheck
Use this when you have one CSV and want to find problems before import.
CSV Compare
Use this when you have two CSVs and want to see what changed.
CSV Repair
Use this when Excel opens the file wrong, characters look garbled, or CSV formatting needs cleanup.
See the difference
Wrong encoding turns readable text into garbled characters. Argon can often clean that up.
Before - Garbled CSV
| Name | City | Specialty |
|---|---|---|
| René | Zürich | Résumé Writing |
| José | São Paulo | Gestão de Projetos |
| François | Montréal | Analyse Financière |
After - Clean UTF-8 CSV
| Name | City | Specialty |
|---|---|---|
| René | Zürich | Résumé Writing |
| José | São Paulo | Gestão de Projetos |
| François | Montréal | Analyse Financière |
How it works
Four steps. Under a minute. No account needed.
Step 1
Upload
Drop your broken CSV file. It stays in your browser — never uploaded to a server.
Step 2
Diagnose
Auto-detects encoding issues, delimiter problems, wrapped one-column rows, and inconsistent row lengths.
Step 3
Preview
See your data in a clean table. Inconsistent rows and parse warnings are flagged.
Step 4
Export
Download a clean UTF-8 CSV with repaired columns, normalized rows, and skipped preambles when detected.
Common fixes
Repairs for everyday CSV problems
Argon CSV Tools handles common CSV cleanup cases when the structure is clear, including Excel delimiter problems and files that open in one column.
Garbled characters from wrong encoding
Semicolon, tab, or pipe-delimited files
CSVs that open as one giant column
Wrapped CSV rows inside quoted text
Inconsistent row lengths
Plain-English CSV help
Got a CSV from a supplier, sales list, or export?
You do not need to know whether the problem is encoding, delimiters, row lengths, or Excel auto-formatting. Argon checks common CSV issues locally in your browser and flags rows that may need review before you open, clean, or import the file.
- Supplier product lists
- Sales or CRM contact lists
- Customer or order exports
- Bank or platform CSV downloads
- Product codes, ZIP codes, IDs, and tracking numbers
Good for files that open weird in Excel, product codes that changed, leading zeros that disappeared, customer lists before CRM import, and CSV files that look broken.
CSV Precheck Report
Check your CSV before Excel or imports change your data.
Argon flags common file-format, spreadsheet, and import-readiness issues locally in your browser. Your CSV contents are not uploaded.
- Weird characters and encoding problems
- CSVs that open in one column
- Uneven rows or repeated headers
- Leading zeros, long IDs, dates, and product codes Excel may change
- Review rows export for rows that need attention
Generate a local precheck summary and optional review rows CSV before importing or opening the file elsewhere.
Open CSV Precheck ToolCSV Precheck FAQ
What the precheck does and does not check
Does Argon upload my CSV?
No. CSV contents are processed locally in your browser and are not uploaded to Argon.
Does Argon promise my CSV will import into Shopify, HubSpot, Salesforce, or another platform?
No. Argon flags common file-format and spreadsheet issues for review. Platform import rules vary, so you should always check the target system’s import requirements.
Can Argon confirm addresses or mailing-list readiness?
No. Argon checks CSV file format only. It does not confirm addresses, list permission, inbox outcomes, or regulatory readiness.
Can Argon help with leading zeros, long IDs, and product codes?
Argon can flag values that Excel may auto-format, such as leading-zero values, long digit strings, and product-code-like values. Review the output before relying on it.
What is the CSV Precheck Report?
The CSV Precheck Report is a local report that flags common CSV structure, Excel-risk, and import-readiness issues. It is generated in your browser.
Import precheck guides
Practical CSV checks before imports and updates
Precheck a Shopify product CSV
Review product CSV headers, rows, SKUs, handles, and values Excel may change before import.
Read guideClean a contact CSV before HubSpot import
Check duplicate emails, blank emails, weird characters, extra spaces, and row issues before import.
Read guideCheck a Mailchimp contact CSV
Find duplicate, blank, and malformed-looking email rows before importing a contact CSV.
Read guideCSV opens in one column in Excel?
Check delimiter issues, semicolons, tabs, and wrapped exports before re-exporting a clean CSV.
Read guideA supplier sent you a CSV?
Inspect supplier product lists, SKUs, IDs, weird characters, and rows before opening in Excel.
Read guideCompare two CSV files before importing
Plan an old-vs-new CSV review around stable keys, changed fields, blank keys, and duplicate keys.
Read guideCompare WooCommerce product CSVs
Compare by SKU or ID and review changed rows before updating products.
Read guideGuides
CSV repair and precheck guides
CSV opens in one column?
Learn how delimiter settings, semicolons, tabs, and wrapped exports can make CSV files open in one column.
fix a CSV that opens in one columnGarbled CSV characters?
Learn why names and accents turn into strange symbols, and how to fix CSV encoding problems.
fix garbled CSV charactersExcel changed your product codes?
Learn why Excel changes leading zeros, long IDs, ZIP codes, and product codes like 4E75.
stop Excel from changing CSV product codesPrecheck a CSV before import
Review encoding, delimiters, headers, row lengths, Excel-risk values, and review rows before uploading a CSV.
precheck a CSV before importFAQ
Why did my CSV open as one giant column?
Some exports wrap each CSV row inside a single quoted field, or use a delimiter your spreadsheet did not detect. Argon CSV Tools checks for common one-column CSV patterns and can reparse wrapped rows into normal columns when it can detect the structure confidently.
Can this fix leading zeros or dates that Excel changed?
No. Leading zeros and automatic date conversion are usually Excel import behaviors, not CSV file damage. To preserve those values, use Excel Data → From Text/CSV import flow and set sensitive columns to Text before importing. Argon focuses on structural CSV problems such as encoding, delimiters, inconsistent rows, and wrapped one-column exports.
How large a file can I process?
Argon CSV Tools is best for small-to-medium CSV files. Because processing happens locally in your browser, performance depends on your device and browser. Very large files may be slow.
Free during launch
Use CSV precheck and repair tools in your browser.
- Upload and preview CSV/TXT files
- Detect encoding and delimiter issues
- Repair wrapped one-column CSV rows when detected
- Export clean UTF-8 CSV
- Optional BOM for Excel
- No account required
- No data leaves your browser
Open CSV Precheck ToolSupport This Tool — $1
Argon CSV Tools is currently free to use. A $1 supporter pass helps fund continued development.