Authenticate Html2Pdf.app requests with the X-API-Key HTTP header. Send a JSON POST to https://api.html2pdf.app/v1/generate, then save a successful synchronous response as PDF bytes. Keep the key in trusted server-side configuration; do not put it in browser code.
What you need to send
Html2Pdf.app’s official documentation specifies this request pattern: the X-API-Key header carries your API key, while the JSON body contains an html field. That field can contain a publicly accessible URL or raw HTML markup. The documented generation endpoint is POST https://api.html2pdf.app/v1/generate. Html2Pdf.app documentation
- Authentication:
X-API-Key: YOUR_API_KEY - Content type:
Content-Type: application/json - Request body: JSON with an
htmlvalue - Successful synchronous response: PDF binary data, not JSON
Get the key and store it safely
- Register with Html2Pdf.app and retrieve the API key sent by email.
- Store it in a server-side environment variable, such as
HTML2PDF_API_KEY, or another trusted secret store. - Make requests only from a backend, server-side script, or trusted job. Do not embed the key in browser JavaScript, a client-side template, or a public repository.
The vendor’s integration examples likewise use server-side invocation or environment-based configuration. Html2Pdf.app documentation Html2Pdf.app
Make a synchronous request with cURL
Set HTML2PDF_API_KEY in your shell before running this command. It sends a public URL for conversion and writes the returned PDF to document.pdf:
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curl --fail --show-error
--request POST https://api.html2pdf.app/v1/generate
--header 'Content-Type: application/json'
--header "X-API-Key: $HTML2PDF_API_KEY"
--data '{"html":"https://www.example.com"}'
--output document.pdfFor raw HTML, replace the JSON value of html with the markup, escaping it correctly as a JSON string. POST is the recommended method. GET is supported, but its query parameters must be URL-encoded; it is a poor fit for raw HTML or long template values. Html2Pdf.app documentation
Use the API from Node.js
This server-side example uses Node.js built-in fetch. It checks the status before writing the response body, and saves the PDF as binary data:
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import { writeFile } from 'node:fs/promises';
const apiKey = process.env.HTML2PDF_API_KEY;
if (!apiKey) throw new Error('Set HTML2PDF_API_KEY first');
const response = await fetch('https://api.html2pdf.app/v1/generate', {
method: 'POST',
headers: {
'Content-Type': 'application/json',
'X-API-Key': apiKey,
},
body: JSON.stringify({ html: 'https://www.example.com' }),
});
if (!response.ok) {
const detail = await response.text();
throw new Error(`Html2Pdf.app returned ${response.status}: ${detail}`);
}
await writeFile('document.pdf', Buffer.from(await response.arrayBuffer()));Do not forward a failed response body as if it were a PDF. Check the HTTP status first, and keep diagnostic output out of logs if it could expose secrets.
Choose between a public URL and inline HTML
Convert a public URL
Put the URL in the html field when the page is publicly reachable by the conversion service. Its stylesheets, fonts, images, and other required resources must also be reachable to the renderer for the intended appearance.
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Convert raw markup
Put HTML markup in the same html field when you need to submit a document directly. Use POST with a JSON body; properly escape quotes, newlines, and backslashes if constructing JSON manually. For nontrivial documents, serialize a language-native object rather than concatenating JSON strings.
Handle synchronous and callback responses
Synchronous generation
By default, the request stays open while the PDF is generated. On success, the response body contains PDF bytes. Check the HTTP status and save or stream those bytes; do not parse them as text or JSON.
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Background generation with a callback
To request background processing, include callBackUrl in the request while continuing to send the API key in the X-API-Key header. The documented immediate response is 202 Accepted: the job has been queued, not completed. Html2Pdf.app later POSTs to the callback URL with the generated document encoded in the callback payload. Confirm the current callback payload and endpoint details in the vendor documentation before implementing a receiver. Html2Pdf.app documentation
Troubleshoot authentication and output
Authentication is rejected
- Confirm that the header is spelled
X-API-Keyand that its value is the key, without placeholder text or accidental whitespace. - Check that the server process actually has
HTML2PDF_API_KEYset. Environment variables available in an interactive shell may not be available to a service or scheduled job. - Do not send the key in the URL or expose it in client-side code. Keep it in the HTTP header from trusted server-side code.
The response is not a PDF
- Check the HTTP status before writing the response as a file. An error response is not PDF data.
- In callback mode, treat
202 Acceptedas queued work. Wait for the callback rather than trying to save the immediate response as the finished document. - For synchronous success, preserve the response as binary bytes; text decoding or JSON parsing can corrupt the file.
The PDF is blank or missing styles, fonts, or images
These are rendering and resource-loading issues, not API-key syntax issues. Html2Pdf.app describes its conversion engine as headless Chromium and notes that CSS media mode, available fonts and resources, and JavaScript load timing can affect the result. Verify that the source URL and its CSS, fonts, and images are publicly reachable, then test representative documents. Html2Pdf.app documentation
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Or skip the browser setup
If your goal is a clean website screenshot rather than a PDF conversion, ScreenshotNeo is a website screenshot API with a single GET request. For example, this cURL call captures a page as WebP; create an API key and see request options in the ScreenshotNeo docs:
curl -G "https://api.screenshotneo.com/v1/shot" -d access_key=YOUR_API_KEY --data-urlencode url=https://stripe.com -o shot.webpScreenshotNeo removes cookie banners, newsletter popups, and chat widgets before capture; bot checks, blank pages, and failed loads are never billed. Its MCP server lets AI agents take screenshots, and the free plan includes 1,000 screenshots a month with no card; paid plans start at $5 for 3,000.
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Frequently Asked Questions
Which header does Html2Pdf.app use for API authentication?
Use X-API-Key with your API key as its value.
Does a successful request return JSON?
No. A successful synchronous generation response contains PDF bytes; save or stream it as binary data.
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