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Convert a URL to PDF in Node.js with axios

The baseline job: give the API a URL, get PDF bytes back. One POST, binary response, no callback dance — the body of the response is the file. Everything else on this page is about doing that reliably: auth, error handling, and not treating a JSON error as a PDF.

Below is a complete, runnable Node.js program using axios (npm install axios). It reads your API key from the SNAPDOK_KEY environment variable — free keys take about thirty seconds and need no card.

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

const res = await axios.post(
  "https://snapdok.io/v1/render",
  {
    url: "https://your-app.com/report/42",
    format: "pdf",
  },
  {
    headers: { "Authorization": `Bearer ${process.env.SNAPDOK_KEY}` },
    responseType: "arraybuffer",
    timeout: 90_000,
  },
);

await writeFile("page.pdf", Buffer.from(res.data));

The response is the document itself with Content-Type: application/pdf. Errors come back as JSON with an error code — which is why every sample here checks the status before writing bytes to disk: the classic integration bug in every language is saving {"error":"UNAUTHORIZED"...} as report.pdf and discovering it a week later.

PDF rendering uses the page's print stylesheet and reflows to paper width, so the width parameter does not apply to PDFs (it is a screenshot concept). If a page looks wrong as PDF, its @media print CSS is usually the culprit. Repeated identical requests inside 24 hours are served from cache — X-Cache: HIT — and not charged.

Same endpoint, one more trick: if the page you are rendering has a form on it, adding "pdf_forms": true to a PDF render brings it back with real, fillable AcroForm fields — a PDF people can type into, not a picture of one. How that works.

Notes for axios

The one axios setting that matters here is responseType: "arraybuffer" — axios defaults to parsing responses as JSON/text, which silently mangles binary bodies. Unlike fetch, axios does throw on non-2xx responses; the error's error.response.data will be an ArrayBuffer too (because of responseType), so decode it with Buffer.from(data).toString() when you want to read the JSON error message. Response headers arrive lower-cased on res.headers.

Response headers worth reading

HeaderMeaning
X-CacheHIT = served from the 24h cache, free.
X-RateLimit-RemainingRequests left in the current second.

Full parameter reference: the docs. Hard numbers on caps and timeouts: limits.

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