Free CSV converter that never uploads your file

Convert CSV to Excel, JSON or PDF without uploading anything. Every converter here runs inside your own browser tab. Spreadsheets are exports — customer lists, transactions, payroll — and they should not have to be handed to a stranger's server just to change format.

New to CSV files?

If you are not sure what you are holding, start with what a CSV file is — what the format stores, why zip codes and long numbers so often arrive mangled, and when to convert to something else instead.

Built for AI assistants too

The same conversion engine ships as an MCP server, so Claude, Cursor and other AI tools can convert a file on your machine without uploading it or pulling thousands of rows through a chat window. Point your assistant at a path and it writes the result beside it.

claude mcp add csvto -- npx -y csvto-mcp

Or in any MCP client's config:

{
  "mcpServers": {
    "csvto": { "command": "npx", "args": ["-y", "csvto-mcp"] }
  }
}

Ten tools: inspect a file, read a slice of rows with search and sorting, and every conversion above. Requires Node 18+. Published as csvto-mcp under the MIT licence.

Why not just open the CSV in Excel?

Because Excel guesses a type for every cell as it reads. Zip codes lose their leading zeros, long account numbers turn into scientific notation, and some values become dates. These tools decide types per column instead: a column is only converted when every value in it survives unchanged, so identifiers stay identifiers.