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Guides for PDF development

Guides, tutorials, and tips for working with PDFs: from free tools to programmatic generation.

Verifactu QR codes on Spanish invoices: a developer guide

What the Verifactu tax QR encodes, the AEAT validation URL, the size and placement rules, and how to render it correctly in an HTML to PDF invoice.

Oct 12, 202611 min read

Developer Guides

One Zod schema, three consumers: REST, MCP, and OpenAPI

How PDF4.dev keeps its REST API, MCP server, and OpenAPI spec aligned, what we actually share today, and the drift we found auditing our own code.

Oct 9, 202610 min read

PDF Security

PDF phishing in 2026: the data, and what it means if you send PDFs

Microsoft, Cisco Talos and Check Point numbers on PDF phishing in 2026, and what a legitimate sender can do so invoices still get delivered.

Oct 7, 20269 min read

AI & PDF

MCP vs A2A for document generation, which protocol exposes your PDF API

MCP lets an agent call a tool. A2A lets an agent delegate a task to another agent. A verified comparison, and what it means for a PDF generation API.

Oct 5, 202610 min read

AI & PDF

MCP Apps: what an interactive PDF preview inside Claude would look like

MCP Apps let an MCP server render interactive HTML inside the chat. Here is what a PDF preview would look like instead of a signed URL you open in a tab.

Oct 2, 202610 min read

Developer Guides

Node.js 26 goes LTS in October 2026: what changes for your PDF Docker image

Node 26 enters LTS on 28 October 2026 and Node 27 starts a one-major-per-year schedule. What it means for a headless Chromium PDF container.

Sep 30, 202611 min read

Developer Guides

Migrating an HTML to PDF pipeline to Puppeteer 25: ESM, Node 22, async executablePath

Puppeteer 25 is ESM-only and needs Node 22.12. The exact package.json, tsconfig and Dockerfile diffs, plus the awaits you now have to add.

Sep 28, 202612 min read

News

OpenAI is shutting down Agent Builder: what it means for document workflows

OpenAI shuts down Agent Builder and the Evals platform on November 30, 2026. Here is how to move a PDF workflow to code before the deadline.

Sep 25, 20269 min read

News

TypeSafe Jev and the System One model: schema-valid is not correct

Jev returns typed decisions instead of text. The output is guaranteed schema-valid, not factually right. Why "zero hallucination" is a misnomer.

Sep 23, 202610 min read

News

CVE-2026-39919: the Ghostscript heap overflow that -dSAFER does not stop

CVE-2026-39919 is a heap buffer overflow in Ghostscript before 10.08.0, reached through a JPEG 2000 image in a PDF. -dSAFER does not mitigate it.

Sep 22, 20269 min read

News

MCP goes stateless: what the 2026-07-28 spec changes for PDF servers

The MCP 2026-07-28 revision drops the initialize handshake and session IDs. Here is what changes for a PDF generation server, with verified spec quotes.

Sep 22, 202611 min read

News

Chrome V8 zero-days in 2026: the threat model of an HTML-to-PDF service

Four of 2026's seven exploited Chrome zero-days hit V8. What that means for HTML-to-PDF: patch cadence, bundled Chromium lag, isolation.

Sep 22, 20269 min read

Developer Guides

How we built a client-side PDF compressor (no uploads, text stays selectable)

Recompressing images inside a PDF with pdf-lib, DecompressionStream, PNG predictors, and OffscreenCanvas workers, entirely in the browser.

Aug 6, 20268 min read

Business Documents

How to generate a purchase order PDF (template + API)

Generate purchase order PDFs from an HTML template with dynamic line items, then render with a headless browser or a hosted API. Node.js and Python code.

Aug 5, 202610 min read

PDF Security

How to add a digital signature to a PDF programmatically

Digitally sign a PDF in code: the difference between a visible signature image and a cryptographic PKCS#7 signature, with Node.js and Python libraries.

Aug 4, 202610 min read

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