Pyntra vs PDF.js vs Puppeteer: Choosing a PDF Stack

"What should we use for PDFs?" is a question that hides three different questions. Displaying a PDF, editing one, and generating one from scratch are distinct problems with distinct best-in-class tools — and choosing the wrong one leads to either a missing capability or a pile of infrastructure you did not need.

This article compares three options developers reach for: PDF.js for viewing, Pyntra for editing and forms and signing, and Puppeteer (headless Chrome) for server-side generation. The honest answer is usually "more than one of them," and the goal here is to make the boundaries clear so you can pick deliberately rather than by inertia.

We will keep the comparison concrete and avoid the trap of pretending one tool does everything. Each is excellent at the job it was built for.

What each tool is actually for

PDF.js is Mozilla's JavaScript PDF renderer — the engine inside Firefox's built-in viewer. It is exceptional at rasterizing and displaying pages in the browser, with a mature text layer for selection and search. It is a viewer. It is not designed to mutate the document's form fields, embed signatures, or re-serialize an edited file with encryption.

Pyntra is a client-side, browser-native PDF editor. It parses a PDF into an editable model and exposes form filling (all field types), drag-to-draw new fields, signature capture and image stamping, annotation (highlight, draw, eraser, redact, crop, shapes), and encryption (RC4 / AES-128 / AES-256) — all in the browser via @pyntra/engine, with zero third-party PDF dependencies and a bring-your-own-UI adapter.

Puppeteer drives headless Chrome on a server. Its sweet spot is generating PDFs from HTML and CSS — invoices, reports, statements — at scale, with no human in the loop. It is a generation and automation tool, running in your backend.

The comparison table

Capability	PDF.js	Pyntra	Puppeteer
Render / view pages	Excellent	Yes (for editing)	N/A (generates, doesn't view)
Text selection & search	Excellent	Basic	N/A
Fill form fields (all types)	No	Yes	No
Add new fields (drag-to-draw)	No	Yes	No
Signature capture & stamping	No	Yes	No
Annotate / highlight / redact	View only	Yes	No
Encrypt (AES-256)	No	Yes	Via extra libs
Generate from HTML templates	No	No	Excellent
Runs in the browser	Yes	Yes	No (server)
Server infrastructure required	None	None	Chrome + queue + autoscale
Document leaves the user's machine	No	No	Yes (sent to server)

Trade-offs that actually matter

The table tells you what each tool does; the decision usually turns on three trade-offs.

• Privacy and data residency. PDF.js and Pyntra keep the document in the browser. Puppeteer, by definition, processes the document on a server — which is fine for documents your system generates, but a real concern for documents a user uploads. If the file is sensitive and user-supplied, a client-side editor like Pyntra removes the question entirely.
• Infrastructure cost. A headless Chrome render farm is one of the more expensive backends to operate: each render is a browser process, so you pay in CPU, memory, cold starts, and queueing. PDF.js and Pyntra cost nothing on the server because they run on the client. For interactive editing at any scale, that difference dominates.
• Capability fit. PDF.js cannot edit. Puppeteer cannot let a user fill and sign an existing PDF interactively. Pyntra cannot generate a fresh document from an HTML template. Trying to force any one tool past its boundary is where projects go wrong.

A viewing-only flow with PDF.js

If all you need is to show a PDF and let users read and search it, PDF.js is the right call. There is no reason to pull in an editor.

import * as pdfjs from "pdfjs-dist";

const task = pdfjs.getDocument({ data: bytes });
const pdf = await task.promise;
const page = await pdf.getPage(1);

const viewport = page.getViewport({ scale: 1.5 });
const canvas = document.querySelector("canvas")!;
canvas.width = viewport.width;
canvas.height = viewport.height;

await page.render({
  canvasContext: canvas.getContext("2d")!,
  viewport,
}).promise;

An editing flow with Pyntra

The moment a user needs to change the document — fill a field, sign, redact — you have crossed out of viewer territory and into editor territory.

import { loadDocument } from "@pyntra/engine";

const doc = await loadDocument(bytes);

// Edit in place, entirely client-side.
doc.fields.set("full_name", "Dana Okoro");
doc.fields.set("agree_terms", true);
await doc.stamp({ image: signaturePng, page: 0, rect: { x: 80, y: 120, width: 200, height: 60 } });

// Save with AES-256, no server round trip.
const out = await doc.save({
  encryption: { algorithm: "AES-256", userPassword: "openWithThis" },
});

This is the gap PDF.js leaves and Puppeteer cannot fill: an interactive editor that mutates a real PDF and re-serializes it without a backend. The full walkthrough — fill, sign, and encrypt entirely in the browser — is in the Pyntra client-side approach.

When to use which

• Use PDF.js when your only requirement is to display PDFs with selectable, searchable text and you never modify the bytes. It is the gold standard for in-browser viewing.
• Use Pyntra when users interact with the document — filling forms, signing, stamping, annotating, redacting, encrypting — especially when the file is sensitive or user-uploaded and you want to avoid server round trips and the infrastructure that comes with them.
• Use Puppeteer (or another server renderer) when you generate documents from templates in bulk, with no human in the loop, and you control the source content.
• Combine them. A common, clean architecture: generate the base document server-side with Puppeteer, render it for review with PDF.js or Pyntra, and let the user fill and sign it client-side with Pyntra. Each tool stays inside its strength.

The trade-offs, the architecture rationale, and the editing model are explored further across the use-cases hub — including a deeper look at the client-side approach and the headless React hooks that make custom editors practical.

There is no single winner here, and any article claiming otherwise is selling something. PDF.js views, Pyntra edits, Puppeteer generates. Match the tool to the verb in your requirement, lean on more than one when the workflow spans verbs, and you will end up with a stack that is both capable and cheap to run.

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PDF.js and Puppeteer are projects/trademarks of their respective owners. Tekivex is not affiliated with, endorsed by, or sponsored by them. Comparisons reflect our understanding at the time of writing; verify current capabilities against each project's official documentation.