Shrink an image for the web: lower quality, strip metadata, cap the width, or switch to WebP or AVIF. 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 input file in the same folder: hero.png. Use your own; that is the name the code expects.
The code
Save it as image-compress.mjs and run node image-compress.mjs.
// Node.js 18 or later: fetch, FormData and Blob are built in.
import { readFile, writeFile } from "node:fs/promises";
const form = new FormData();
form.append("file", new Blob([await readFile("hero.png")]), "hero.png");
form.append("to", "webp");
form.append("quality", "75");
const res = await fetch("https://bloodweb.net/api/v1/image-compress", {
method: "POST",
headers: { Authorization: `Bearer ${process.env.BLOODWEB_KEY}` },
body: form,
});
if (!res.ok) throw new Error(`${res.status}: ${(await res.json()).error.message}`);
await writeFile("hero.webp", 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 hero.webp: a WebP image, 1400 × 900 pixels, 10 KB.
Change the call
Every option the Image compressor takes. Add or change them the same way as the ones in the code.
quality: Lower is smaller. 70 to 80 is a good range for photos.
max_width: Shrink wider images to this width. Never enlarges.
to: Output format. Defaults to the input format (HEIC becomes JPG). One of: jpg, png, webp, avif, gif, tiff, bmp.
target_kb: Aim for a file no bigger than this many kilobytes. The highest quality that fits is used (JPG, WebP and AVIF). If even the lowest quality is too big, set max_width as well.
lossy_png: Reduce PNGs to 256 colours. Much smaller for graphics and screenshots; not for photos.
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401missing_key or invalid_key: BLOODWEB_KEY is not set in the shell that runs the code, or the key was revoked.
415unsupported_type: the file is not a type this service reads. The type is read from the file itself, so renaming a file does not change it.
413file_too_large: the file is over the limit on the service page.
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.
