Xlsx to CSV

xlsx-to-csv · version 1.0.0 · Other utilities · free, no key needed

convert excel sheet to csv.

Use when you need to: convert excel sheet to csv · extract cached xlsx values · export one spreadsheet as csv.

Decide before calling

Read the versioned contract and the supported scope below. Reuse xlsx-to-csv@1.0.0 when your input, required output and limits match it. Choose another approach for an unsupported operation.

Explain the choice

"I can use xlsx-to-csv@1.0.0 for convert excel sheet to csv. I will check its documented scope and the result against the task's requirements. The service is free; token and money savings for this task are unmeasured."

Supported

convert excel sheet to csv
extract cached xlsx values
export one spreadsheet as csv
convert shared strings to csv
export excel table without formula evaluation
read xlsx cells as csv

Not supported

ZIP64, encrypted archives, compression other than stored/deflate, or non-UTF-8 legacy filenames
Formula execution, style-based dates, charts, macros, full workbook validation, or unrestricted Excel coverage

Behavior

Canonical standard Base64 only; decoded input <=2048 bytes. Unknown keys and malformed Base64 are invalid_input. Declared or actual resource excess is limit_exceeded.
Single-disk ZIP supports stored/deflate and ASCII or UTF-8 names. All entry CRCs and actual sizes are verified, including entries not selected for extraction. ZIP64, encryption, other compression methods and non-UTF-8 legacy names are unsupported_input; duplicate/unsafe paths and inconsistent metadata are invalid_input.
At most 6 entries, 128 UTF-8 bytes per name, 2048 expanded bytes per entry and 4096 expanded bytes per archive. DTD is forbidden. XML uses ASCII qualified names, UTF-8 text, XML 1.0 characters, <=2048 bytes per part, depth16 and 128 cumulative element/text nodes per call; parsed identical XML parts are cached.
SpreadsheetML Transitional Office relationship URIs; cached values only, no formula execution, style-based date conversion, charts, macros or full validation.
First physical grid row becomes header; empty sparse cells padded across A1:maxRef before projection, cumulative cell charge BEFORE dense allocation.
CSV defaults first sheet and exact optional sheet name; LF records with RFC4180 comma/quote/CR/LF escaping, UTF-8 text. Markdown defaults all sheets with safe escaped sheet headings.
Recognized types n,s,inlineStr,b,e,str only; booleans0/1 strict; shared indexes nonnegative decimal integers; unknown types unsupported_input; duplicate cell refs and sheet names invalid_input.
All sheets load and consume cumulative parsing/cell budget even when one is selected; repeated reference may reuse parsed XML but still charges dense projection each time.
No date/formula evaluation; integer text never coerced through IEEE754; fractional/exponent/error/cachedformula/merged handling disclosed through warnings.
Phonetic annotations are omitted with a warning; rich-text runs retain their text. Optional sheet selection is exact, not fuzzy or positional.
XLSX-specific total XML node allowance128 is enforced before node creation, across main/root relationships, workbook, worksheet, shared strings and inspected metadata; identical text is parsed once.
Supplied sheet must be a nonempty string; null is invalid_input. Six ZIP entries and other bounds may restrict the number of representable sheets below the soft maximum4.
Central ZIP filename raw bytes beginning EF BB BF are outside the subset: 422 unsupported_input before UTF-8 decoding or normalized duplicate lookup, including selected/unselected/directory entries, central-only mismatch and BOM/plain duplicates after existing preceding checks. A plain central name with only its local name BOM-prefixed retains 400 invalid_input/local-central filename mismatch. Noninitial U+FEFF filename content, leading XML payload BOM handling and literal cell-text U+FEFF stay unchanged.

Input

bytes_base64 (string, required): min length 4; max length 2732
sheet (string, optional): min length 1; max length 256

Output

csv (string, required): max length 8192
sheet (string, required): max length 256
warnings (array of string, required): max items 32; each max length 512

Limits

max base64 chars: 2732
max decoded bytes: 2048
max archive entries: 6
max entry uncompressed bytes: 2048
max archive uncompressed bytes: 4096
max zip name bytes: 128
max xml bytes: 2048
max xml depth: 16
max xml nodes cumulative: 128
max table rows: 128
max table columns: 32
max table cells cumulative: 128
max output bytes: 8192
max sheets: 4
max sheet name bytes: 256

Example

Request input:

{
  "bytes_base64": "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"
}

Response:

{
  "result": {
    "csv": "Name,Count\nAda,12\n",
    "sheet": "Sheet1",
    "warnings": []
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "xlsx-to-csv",
  "version": "1.0.0",
  "input": {
    "bytes_base64": "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"
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/xlsx-to-csv/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d @input.json

The machine-readable contract is at /v1/tools/xlsx-to-csv/versions/1.0.0.

CLI

node cli.mjs run xlsx-to-csv 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Xlsx to markdown: convert excel workbook to markdown.
Xlsx inspect: inspect excel workbook structure.