Excel to Protocol Buffers schema API

Code examples

These examples send the sample as multipart/form-data and save the returned bytes unchanged. Set TABLECONVERT_API_KEY in your environment.

curl --fail-with-body --max-time 40 \
  'https://api.tableconvert.com/v2/convert/excel-to-protobuf' \
  --header "Authorization: Bearer $TABLECONVERT_API_KEY" \
  --form 'file=@excel-to-protobuf-input.xlsx' \
  --output 'excel-to-protobuf.protobuf.txt'

import os
from pathlib import Path
import requests

endpoint = "https://api.tableconvert.com/v2/convert/excel-to-protobuf"
headers = {"Authorization": "Bearer " + os.environ["TABLECONVERT_API_KEY"]}
fields = {

}

with open("excel-to-protobuf-input.xlsx", "rb") as source:
    files = {**fields, "file": ("excel-to-protobuf-input.xlsx", source)}
    response = requests.post(endpoint, headers=headers, files=files, timeout=40)
response.raise_for_status()
Path("excel-to-protobuf.protobuf.txt").write_bytes(response.content)

import { readFile, writeFile } from "node:fs/promises";

const form = new FormData();
form.set("file", new Blob([await readFile("excel-to-protobuf-input.xlsx")]), "excel-to-protobuf-input.xlsx");

const response = await fetch("https://api.tableconvert.com/v2/convert/excel-to-protobuf", {
  method: "POST",
  headers: { Authorization: "Bearer " + process.env.TABLECONVERT_API_KEY },
  body: form,
  signal: AbortSignal.timeout(40_000),
});
if (!response.ok) {
  throw new Error("HTTP " + response.status + ": " + await response.text());
}
await writeFile("excel-to-protobuf.protobuf.txt", Buffer.from(await response.arrayBuffer()));

Request parameters

The API reads the first worksheet of an uploaded workbook as cell values and normalizes it into table rows. It does not preserve the workbook’s formulas, charts or visual design.

Send one source: data, file, or url. The examples below use the source mode appropriate for this format.

Output options

Generate a proto3 message definition followed by a JSON representation of row data. The combined text is neither protobuf wire encoding nor a standalone compilable .proto file.

This output format does not expose additional options.

Conversion rules

How the input is read

• Place the intended data in the first worksheet, using a simple rectangular range with a deliberate first-row header.
• The conversion uses extracted cell values, not the spreadsheet as an executable calculation model.
• Only the first extracted worksheet is converted. There is no input sheet-selection parameter, and workbook sheets are not merged.
• Review date displays, leading zeros and large identifiers after extraction; original Excel types and formatting do not transfer to every target.

How the output is written

• Header names become string fields numbered from one.
• Separate the message definition from the appended JSON before using protoc or a protobuf library.
• Validate field identifiers, reserved words and long-term field numbering before using the draft schema.

When to use this API

Responses and errors

Check the response before retrying. A new HTTP request is a new conversion and may use credits again.

Limits, billing and versions

Local previews accept up to 200 KB. The current API implementation allows one uploaded file up to 50 MiB, limits each multipart text field to 1 MiB, and gives v2 conversion tasks a 30-second deadline. Deployment limits may be stricter. Read the returned error before retrying; some parser or renderer failures return HTTP 500.

Live calls follow the API credit policy. Failed conversions are refunded; a completed conversion is not undone if the download connection later fails.

References and format specifications

Format references explain the underlying syntax. The conversion rules and samples above describe TableConvert’s implementation.

• docs.sheetjs.com
• protobuf.dev