How to Merge PDF Files with One API Call

Merging PDFs server-side usually means installing and maintaining native libraries. A REST call removes the dependency.

Provide file URLs or base64 content; the service returns the merged PDF as a base64 string plus the page count.

The endpoint

POST /merge takes a JSON body with a "files" array of two or more inputs. Each entry is either {"base64": "..."} or {"url": "https://..."}, in any combination. Array order defines page order.

Quick start

curl -X POST "https://pdf-toolkit2.p.rapidapi.com/merge" \
  -H "X-RapidAPI-Key: YOUR_KEY" \
  -H "X-RapidAPI-Host: pdf-toolkit2.p.rapidapi.com" \
  -H "Content-Type: application/json" \
  -d '{"files":[{"url":"https://example.com/a.pdf"},{"url":"https://example.com/b.pdf"}]}'

Saving the result

The response is {"pdfBase64": "...", "pageCount": n}. Decode pdfBase64 to bytes to get the merged file.

const res = await fetch("https://pdf-toolkit2.p.rapidapi.com/merge", {
  method: "POST",
  headers: {
    "X-RapidAPI-Key": "YOUR_KEY",
    "X-RapidAPI-Host": "pdf-toolkit2.p.rapidapi.com",
    "Content-Type": "application/json",
  },
  body: JSON.stringify({ files: [{ url: "https://example.com/a.pdf" }, { url: "https://example.com/b.pdf" }] }),
});
const { pdfBase64, pageCount } = await res.json();
require("fs").writeFileSync("merged.pdf", Buffer.from(pdfBase64, "base64"));
console.log("pages:", pageCount);

The rest of the toolkit

/split extracts pages or page ranges into a new document. /info returns page count, dimensions, and metadata. /watermark stamps diagonal text across every page. /rotate turns pages 90, 180, or 270 degrees.