Show HN: A graph paper generator that renders vector PDFs in the browser

Show HN: A graph paper generator that renders vector PDFs in the browser(freegraphpaper.net)

46 points by lam_hg94 4 hours ago | 9 comments

Topology1 48 minutes ago |

Any chance that a pentagon pattern could be added?

ChrisMarshallNY 2 hours ago |

Very cool.

However, on Safari, in the Mac, I don't see any graph on the first two (standard North-South/East-West graph).

I do see the isometric and hexagonal ones, though. Maybe the lines are too thin/light.

fortran77 44 minutes ago |

Nice, but I'd love more log options, and a log-linear. And a Smith chart.

smalltorch 2 hours ago |

This is a nice sharply pointed tool. Thanks for the nice supply of pre configured styles!

chrisweekly 2 hours ago |

Cool! Thanks for creating and sharing this!

lam_hg94 4 hours ago |

I got tired of graph-paper sites that print at the wrong scale, hide the PDF behind a signup, or slap a watermark on it. So I built one that's free, has no login, and prints true-to-scale.

The interesting part for me was the architecture: a single pure function buildPaper(config) emits geometric primitives (lines / circles / text), and everything is derived from it - the on-screen SVG preview, the in-browser PDF, and the build-time PDF and OG-image generation. No drawing logic is duplicated across output formats, so adding a new paper style is one renderer function plus about five one-line registrations, and it automatically gets a live preview, a downloadable PDF, an OG image, and SEO pages across every paper size.

Everything is true-to-scale: the SVG viewBox and the PDF are both in millimetres, so a 5 mm grid measures exactly 5 mm on paper when you print at 100%.

It's fully static - no backend, no database, no runtime. About 1,900 pages are prerendered to HTML, ~1,700 PDFs are pre-generated at build time (reusing the exact same draw logic as the browser), and it all deploys to a CDN as plain files.

Tech stack:

- Nuxt 4 / Vue 3 (script setup, TypeScript), Nitro static generation (nuxt generate) - Tailwind CSS v4 plus scoped CSS with a small design-token system - Paper engine: one pure buildPaper() -> primitives; one renderer per style. Single source of truth for preview + PDF + images - Preview: pure renderPaperSvg() -> inline SVG baked into the prerendered HTML, so previews render with zero client JS - PDF: jsPDF (dynamic import) for arbitrary custom configs in the browser; a Bun script reuses the same primitives to pre-build the static PDFs - Social images: SVG -> PNG at build time with @resvg/resvg-js (1200x630 OG per style + full A4 sheets) - Data-driven pSEO: ~40 styles across the full ISO A/B/C and US/Imperial sizes -> ~1,900 pages generated from one data table; JSON-LD (WebSite/HowTo/FAQ/Breadcrumb); selective noindex on low-demand size combos so thin pages don't dilute the site - Tooling: Bun (package manager + native-TS runner for all the generators) - Hosting: Cloudflare Pages, pure static (no worker)

There's also a custom editor (tweak spacing, color and margins, then export) and a virtual graph-paper canvas you can draw on, where the logical drawing space is decoupled from the pixel buffer so it stays crisp on any DPR.

One war story: because Cloudflare Pages serves pages at trailing-slash URLs, the client router saw /foo/ while my lookup table keyed on /foo - so pages rendered correctly server-side, then hydrated straight into a 404. Classic "works with JS off, breaks with JS on."

Happy to answer anything about the rendering pipeline or the static-generation setup.

indianmouse 1 hour ago | |

Very nice implementation.

Really appreciate it.

Solves a lot of issues with the other sites. Though I haven't used it much or need it, it could be useful to students who need it and one PDF of it solves the issue.

Just keep it running. Have you considered open sourcing it at some point?

genewitch 2 hours ago | |

is there a way to export the .svg so i can load them into a plotter to make the graph paper? Since you've expended all the effort to ensure proper sizing and whatnot. It even looks like it has the same margins as my plotter!

Theodores 1 hour ago | |

DRY applies, even in SVG. Draw one horizontal line and then reuse it for the other horizontal lines. Same for the vertical lines. The advantage of this technique is that you can clone the master lines without having to repeat yourself with the stroke-width and other attributes. You can also specify just the x or just the y of the cloned line, thereby needing to specify x1, x2, y1 and y2 just once per master line, with x (or y) in the use elements being just the offset.

Why bother? DRY. That is it.

If you put the master lines in a 'defs' as symbols, then they can inherit some attributes from a 'g' (group), therefore enabling you to specify stroke-width just once. Non-scaling stroke widths can also be specified, meaning that you can scale up an A4 to an A0 without having fat lines.

Since you want to make graph paper accessible to all, you can put a few words together in the 'desc' for that, and give the paper a 'title' specifying what it is, e.g. A4, 5mm spacing, with your URL.

Nobody will ever care for these small changes, however, if you branch out into making paper for composers or other specialist use cases, these techniques might come in hand.