Merge, split, compress and password-protect PDFs

Pick a folder of PDF files and run pdfcpu, an open-source PDF processor, on all of them: merge them into one document, split them into single pages, optimize them, or add and remove password protection. It runs in this tab; your documents are never uploaded.

What you can do

mkdir -p out && pdfcpu merge -c disable out/merged.pdf *.pdf

mkdir -p out/split && st=0; for f in *.pdf; do [ -e "$f" ] || continue; pdfcpu split -c disable --force "$f" out/split 1 || st=1; done; exit $st

mkdir -p out && st=0; for f in *.pdf; do [ -e "$f" ] || continue; pdfcpu optimize -c disable "$f" "out/${f%.pdf}-optimized.pdf" || st=1; done; exit $st

mkdir -p out && st=0; for f in *.pdf; do [ -e "$f" ] || continue; pdfcpu encrypt -c disable --upw "$PDF_PASSWORD" --opw "$PDF_PASSWORD" "$f" "out/${f%.pdf}-locked.pdf" || st=1; done; exit $st

mkdir -p out && st=0; for f in *.pdf; do [ -e "$f" ] || continue; pdfcpu decrypt -c disable --upw "$PDF_PASSWORD" "$f" "out/${f%.pdf}-unlocked.pdf" || st=1; done; exit $st

pdfcpu info -c disable *.pdf

How it works

1. Pick a folder. Choose the folder with your PDF files. They are copied into a sandbox in this browser tab, not uploaded.
2. Choose an operation. Merge, split, optimize, add a password, remove a password, or show document info. The matching pdfcpu command appears and can be edited.
3. Run pdfcpu. Press Run. pdfcpu, compiled to WebAssembly, processes the files and writes the results into an out/ folder.
4. Save the results. Save out/ back into your folder, or download it as a zip file.

Under the hood the page boots NanoVM, a Linux userland compiled to WebAssembly, in this tab. Your folder is copied into its in-memory filesystem at /work, and a BusyBox shell runs the command, which starts pdfcpu on the WebAssembly (WASI) runner. The Terminal tab opens the same folder in an interactive shell, for anything the presets don’t cover.

Your files stay on your device

Your PDFs are read by your browser and copied into an in-memory filesystem inside this tab, where pdfcpu (compiled to WebAssembly) processes them. Nothing is uploaded; there is no server that could receive them.

Passwords you type are passed to pdfcpu as an environment variable for that one run. They are not part of the command line, the share link or any request.

The only network requests are for the pdfcpu program itself: a signed, content-hashed package from the jsDelivr CDN, fetched once and cached. The counter next to the Run button lists every request that leaves this site.

Questions

The software

program

pdfcpu 0.16.1

license

Apache-2.0

source

github.com/pdfcpu/pdfcpu

runs on

WebAssembly (wasm32-wasip1) on the host wasm engine

delivered as

a signed, content-addressed package from the NanoVM app catalog (Ed25519 + SHA-256, verified in the browser)

this page

AGPL-3.0-only OR LicenseRef-UEL · source

Build the same thing into your page

This tool is the <nano-tool> web component from the public NanoVM SDK (@userland-run/nano-sdk/tools), with the built-in pdf definition. The same element runs on any page:

<script type="module">
  import { defineNanoTool } from "@userland-run/nano-sdk/tools";
  defineNanoTool();
</script>
<nano-tool tool="pdf" wasm-url="/nano.wasm" terminal url-params></nano-tool>

Or headless, with the folder bridge (@userland-run/nano-sdk/folder). Definitions are plain data — presets, form fields and quoted command templates — so you can write one for any catalog app.

import { createNano } from "@userland-run/nano-sdk";
import { mountFolder } from "@userland-run/nano-sdk/folder";
import { runTool } from "@userland-run/nano-sdk/tools";

const nano = await createNano({ image: { wasm: "/nano.wasm" }, ramMB: 512 });
const dir = await showDirectoryPicker({ mode: "readwrite" });
const folder = await mountFolder(nano, dir, { at: "/work" });
// installs pdfcpu from the signed catalog, then runs:
// mkdir -p out && pdfcpu merge -c disable out/merged.pdf *.pdf
const r = await runTool(nano, { tool: "pdf", preset: "merge", folder });
if (r.exitCode === 0) await folder.writeBack(); // new and changed files only; never deletes

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