Extract markdown in TypeScript with fetch

format is pdf by default and markdown is one of its alternatives. The response is still the receipt with a download url; fetching it serves the extracted markdown as text/markdown, and the download's Content-Disposition names the file with an .md extension even though the url itself keeps its .pdf suffix.

The recipe

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

const ORIGIN = "https://webcapture.io";

const res = await fetch(`${ORIGIN}/v1/convert`, {
  method: "POST",
  headers: {
    "Authorization": "Bearer wc_your_key",
    "Content-Type": "application/json",
  },
  body: JSON.stringify({"url": "https://example.com/", "format": "markdown"}),
});
const receipt = await res.json();

// receipt.download: ${ORIGIN}/v1/conversions/cnv_ec487efd8c301fc8.pdf
// the url keeps its .pdf suffix, but the bytes are markdown:
const file = await fetch(receipt.download, {
  headers: { "Authorization": "Bearer wc_your_key" },
});
// text/markdown; charset=utf-8
console.log(file.headers.get("content-type"));
await writeFile("page.md", await file.text(), "utf8");

Markdown extraction runs in the same quota and behind the same key as pdf: one extraction is one document against the month's count. Extraction reads the rendered page, so JavaScript already ran and the receipt's bytes field counts the markdown, which is usually a few kilobytes.

Same-key GET: 401 without it; 404 for another key.

The fields this recipe uses

• format: pdf is the default; markdown extracts the rendered page's text as markdown instead of printing it.

Related

• Next: Get a free key to run this TypeScript recipe, or read the API docs.
• More recipes: TypeScript: convert from a URL, TypeScript: dark mode, Node: convert from a URL.
• The webcapture API reference: every field the convert endpoint admits, with the response shapes and the error table.
• The recipes hub: the same endpoint in the other languages.
• Going deeper: markdown output is a differentiator: the comparison grid marks it ours-yes, theirs-no.
• The free URL to PDF tool: try the render in a browser before you wire the call.

Method

Source: convert field reference, checked 2026-10-05. Corrections.