> For the complete documentation index, see [llms.txt](https://doc.duaer.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://doc.duaer.com/tools.md).

# Free file converters from Duaer

Free Duaer tools for spreadsheets and data files: convert formats, merge, split, remove duplicates, fix encodings, and format JSON. Everything runs in your browser and no file is uploaded.
## Tools

- [CSV to Excel](/tools/csv-to-excel.md): detects UTF-8 or GBK and keeps long numbers as text.
- [Excel to CSV](/tools/excel-to-csv.md): UTF-8 with BOM so Excel reopens it cleanly.
- [JSON to CSV](/tools/json-to-csv.md): nested fields become columns like `customer.name`.
- [CSV to JSON](/tools/csv-to-json.md): the first row becomes field names, one record per row.
- [Markdown table to Excel](/tools/markdown-table-to-excel.md): paste a table from an AI chat.
- [Word table to Excel](/tools/word-table-to-excel.md): one sheet per table in a .docx.
- [PDF table to Excel](/tools/pdf-table-to-excel.md): rebuilds rows and columns from text PDFs.

## Clean up tables

- [Merge Excel or CSV files](/tools/merge-excel-files.md): columns aligned by header, optional source-file column.
- [Split a table by column](/tools/split-table-by-column.md): one sheet per department, region, or any column value.
- [Remove duplicate rows](/tools/remove-duplicates.md): pick the columns that define a duplicate and keep the first row.
- [GBK / UTF-8 converter](/tools/gbk-utf8-converter.md): fix garbled CSV and TXT files either way.
- [JSON formatter and validator](/tools/json-formatter.md): format, minify, and find the line and column of an error.

## Where your file goes

These Duaer tools read the file and build the result inside your browser. Nothing passes through Duaer servers, and closing the tab discards the data.
## Questions

### Are the Duaer converters free?

Yes, and no sign-in is needed. You only register for Duaer when you want the conversion to run automatically as a digital organization.

### Does Duaer upload my file?

No. The Duaer converters run in your browser, and the file never leaves your computer.

## Related

- [CSV to Excel converter (free, no upload)](https://doc.duaer.com/tools/csv-to-excel.md)
- [Excel to CSV converter (UTF-8, no upload)](https://doc.duaer.com/tools/excel-to-csv.md)
- [JSON to CSV converter (nested JSON flattened)](https://doc.duaer.com/tools/json-to-csv.md)
- [CSV to JSON converter (free, no upload)](https://doc.duaer.com/tools/csv-to-json.md)
- [Markdown table to Excel (works on AI chat tables)](https://doc.duaer.com/tools/markdown-table-to-excel.md)
- [Word table to Excel converter (.docx)](https://doc.duaer.com/tools/word-table-to-excel.md)
- [PDF table to Excel converter (text PDFs)](https://doc.duaer.com/tools/pdf-table-to-excel.md)
- [Merge Excel and CSV files online (columns matched by header)](https://doc.duaer.com/tools/merge-excel-files.md)
- [Split an Excel table by column online (one sheet per value)](https://doc.duaer.com/tools/split-table-by-column.md)
- [Remove duplicate rows from Excel or CSV online](https://doc.duaer.com/tools/remove-duplicates.md)
- [GBK to UTF-8 converter online (fix garbled CSV and TXT)](https://doc.duaer.com/tools/gbk-utf8-converter.md)
- [JSON formatter and validator online (shows error line and column)](https://doc.duaer.com/tools/json-formatter.md)