vellora

HTML to PDF for Node.js, native and browserless by default.

vellora renders generated document HTML - invoices, receipts, statements, boletos, notifications - through a native napi-rs addon. The default path does not install Puppeteer, Playwright, Chromium, or a sidecar service.

npm install vellora

Supported prebuilds today: macOS arm64/x64 and Linux glibc x64/arm64. musl/Alpine and Windows prebuilds are not published yet.

Quick Start

import { renderPdf } from "vellora";

const pdf = await renderPdf(invoiceHtml, data, {
  metadata: { title: "Invoice INV-2026-00417", creationDate: "2026-06-23T00:00:00.000Z" },
  strict: true,
});

Use the native path when your template fits vellora's documented subset. For templates that need browser print fidelity, install the optional engine and provide a Chrome/Chromium executable:

npm install vellora @vellora/engine-chromium

const pdf = await renderPdf(html, data, {
  engine: "chromium",
  chromium: { executablePath: "/path/to/chrome", timeoutMs: 30_000 },
});

What Ships In 0.1.0

Area	Status
Native render API	renderPdf, renderPdfBatch, renderPdfToStream
Templates	{{ value }}, {% if %}, {% for %}, currency, number, date
Strict subset validation	Default behavior; unsupported input rejects before PDF output
Best-effort fixing	{ strict: false } runs @vellora/lint fixers before render
Assets	Caller-supplied image bytes, data URL images, custom font bytes
PDF output	Deterministic bytes, selectable text, embedded font subsets, metadata, PDF/A-2b
CLI	vellora render, lint, fix, doctor, fidelity
Fidelity routing	engine: "native", engine: "chromium", and engine: "auto" policy files

Compatibility

vellora is not a browser clone. It targets generated documents whose markup you control.

Supported or documented today:

• block and inline text, headings, lists, and tables, including repeated <thead> across pages
• @page margins, page counters, running headers/footers
• PNG, JPEG, GIF, and WebP images via data URLs or the images option
• custom TTF/OTF font bytes via the fonts option
• PDF/A-2b archival output
• partial flexbox behavior; prefer tables for reliable document layout
• dev-time fixes for common issues such as inline SVG and grid/flex inside table cells

Unsupported on the native path:

• JavaScript execution and browser APIs
• arbitrary website rendering
• network fetching of image/font assets
• interactive forms, media elements, canvas, iframe/object/embed
• full CSS grid/flex/browser layout fidelity

The generated source of truth is COMPATIBILITY.md.

Evidence

Visual evidence is generated from the repo fixtures against the optional Chromium engine: report, manifest.

_{Invoice fixture: native render and native-vs-Chromium diff.}

Resource numbers come from Resource Benchmarks run 28302742627 on pinned Linux CI, Node v22.23.0, 4 cores:

Path	Fresh install	External runtime	RSS @8	External RSS @8	Warm median / p95
Native vellora	28.93 MB	N/A	116.51 MB	N/A	17.47 / 17.96 ms
Vellora Chromium	28.94 MB	412.28 MB	N/A	6425.81 MB	491.85 / 509.43 ms

Puppeteer and Playwright are included in the benchmark artifact but are not quoted as comparable here because that run marked them non-comparable for the fixture (page count 1 != reference 3).

Packages

Package	Purpose
vellora	Public API, templating, orchestration
@vellora/native	Host prebuild loader for the napi addon
@vellora/lint	Dev-time diagnose() and fix()
@vellora/cli	Command line workflows
@vellora/engine-chromium	Optional browser-fidelity engine using a host-supplied Chrome/Chromium

Docs

• Docs site
• COMPATIBILITY.md
• ARCHITECTURE.md
• benchmarks/
• RELEASING.md
• SECURITY.md

License

MIT - see LICENSE.