Prepare an import file
Fit your source data to a destination template. Map columns, fill defaults, convert values and resolve missing required fields before downloading.
1 Load your data
Up to 5 MiB. Loading new data replaces the current source and mappings.
Or paste text
Preview the first 5 data rows
No data loaded.
2 Load the destination template
The first row defines the exact output column names and order. Other template rows are ignored. Required fields and defaults are set below.
3 Map to the required output
Unique column-name matches are suggested, ignoring case and surrounding spaces. Check each mapping. Use one source column more than once if needed.
Defaults fill unmapped fields and blank or whitespace-only source values, before conversion. Defaults must match the chosen input format. Optional unmapped fields remain blank. Required checks run after conversion.
About value conversions
Text conversions trim surrounding whitespace. Dates use the explicit order selected and output YYYY-MM-DD, without time zones. Numbers use the selected decimal and thousands separators, preserve all decimal digits and expand exponents. They remove leading zeroes: keep IDs as original text. Accounting parentheses represent negative numbers; currency symbols are not accepted. Blank cells are kept unless a default is set. Failed conversions remain visible in the preview and block import-file export.
4 Review and download
Off by default to preserve exact import values and column names. Protection adds an apostrophe to cells starting with formula characters, including negative numbers, in both CSV and TSV. Enable it if opening the file in a spreadsheet; check your destination accepts the added characters.
First 100 output rows shown. Copy and download include every row. Data row numbers in issue reports count from the first source data row.
No output yet.
View formatted output
Preview limited to 30,000 characters. Copy and download include the complete output.
Prepare for your destination
Load source data and the destination system’s CSV or TSV template. Header-only templates work. Names and column order are preserved exactly; blank, duplicate or overlong template names must be corrected. Sample template rows do not supply defaults or validation rules.
Choose each source field, add fallback defaults and mark the fields your destination requires. All source rows are kept, and extra source columns are left out of the output. Changing either input resets mappings. Changing any mapping clears the previous result. Every preview starts from the loaded source.
Resolve every missing required value and failed conversion before exporting the import file. You can download the issue report while the import file is blocked. Checks cover only the rules selected here; your destination may have additional constraints.
Privacy and limits
Files, templates, mappings and results stay in browser memory. They are not uploaded, stored or added to URLs. Clear all data cancels processing and clears both inputs and settings. Clipboard and downloads act only when selected. Only theme preference is stored. See privacy and analytics.
Each input allows 5 MiB. Tables allow 20,000 data rows, 100 columns, 500,000 cells including headers and 20 million characters. Defaults allow 1,000 characters; template names allow 200. Reports allow 100,000 issues and 20 million characters. Exports allow 20 million characters. Decimal conversions allow 1,000 digits.
Source files can be UTF-8 CSV, TSV, JSON, JSON Lines or Excel, using the shared converter’s limits. Choose a worksheet or JSON collection when needed. Excel formulas use saved results; use displayed text for formatted dates. Malformed or uneven CSV rows block loading. Source headers are trimmed and made unique with warnings; destination headers are preserved.
Hosted processing uses a local browser worker with a 20-second deadline per operation. Opening this page directly uses the same engine on the page and can pause with large inputs. Modern browsers with workers, TextEncoder, File.arrayBuffer and Blob URLs are required. Clipboard may need HTTPS or permission. Excel uses the locally bundled Apache 2.0 licensed SheetJS library.