Make a QR code from a URL or text, as PNG or SVG, in your colours, with your logo in the centre if you like. Here is the whole call in Node.js, with the output it produced when we ran it.
Before you start
An API key. Create a free account; it comes with free tokens every month. Put the key in an environment variable so it stays out of your code: export BLOODWEB_KEY=your_key
Node.js 18 or later. Nothing to install: fetch, FormData and Blob are built in. Save the file with the .mjs ending so await works at the top level.
The code
Save it as qr-generate.mjs and run node qr-generate.mjs.
// Node.js 18 or later: fetch, FormData and Blob are built in.
import { writeFile } from "node:fs/promises";
const url = new URL("https://bloodweb.net/api/v1/qr-generate");
url.search = new URLSearchParams({ data: "https://example.com", size: "300" });
const res = await fetch(url, {
headers: { Authorization: `Bearer ${process.env.BLOODWEB_KEY}` },
});
if (!res.ok) throw new Error(`${res.status}: ${(await res.json()).error.message}`);
await writeFile("qr.png", Buffer.from(await res.arrayBuffer()));
What you get
Tested 19 October 2026: this exact code ran against our test copy of the API, which runs the same service code as bloodweb.net, and produced this.
It writes qr.png: a PNG image, 300 × 300 pixels, 1 KB.
Change the call
Every option the QR code generator takes. Add or change them the same way as the ones in the code.
datarequired: What the code holds: a URL, text, a vCard, a Wi-Fi string.
format: Image format. One of: png, svg.
size: Width and height in pixels, including the margin.
margin: Quiet zone around the code, in modules. Scanners want 4; less works on plain backgrounds.
ecc: Error correction: L 7%, M 15%, Q 25%, H 30%. Higher survives damage or a logo, but makes a denser code. One of: L, M, Q, H.
color: Module colour.
background: Background colour, or "transparent".
logo_size: Logo width as a percentage of the code. Bigger logos are harder to scan.
If it fails
A failed call is not charged. The answer is JSON with an error object; the code above prints its message. The usual ones:
401missing_key or invalid_key: BLOODWEB_KEY is not set in the shell that runs the code, or the key was revoked.
400bad_param: a value is wrong or missing. The message names the parameter.
402insufficient_tokens: the balance does not cover the call. Top up in the dashboard.
429rate_limited: too many calls at once. Wait the seconds in the Retry-After header and send it again.
