A deterministic, fully client-side web app that converts GURPS Third Edition material into Fourth Edition using your own legally-obtained GURPS PDFs. It shows the original 3e block, an audit of exactly what changed (with the governing rule quoted), and a reconstructed 4e block — then lets you export a clean, GURPS-supplement-styled document.
Live demo: https://ceearrbee.github.io/gurpslite-3e-to-4e/
Important
This is an unofficial fan project. It is not affiliated with, endorsed by, or licensed by Steve Jackson Games. GURPS is a trademark of Steve Jackson Games, and its rules are copyrighted by Steve Jackson Games. No GURPS content is included in or distributed with this repository. The converter works only on PDFs you supply, and is offered under the permissions of the Steve Jackson Games Online Policy. See Legal below.
- Deterministic conversion, nothing is hard coded. It parses the Quick-and-Dirty conversion tables out of GURPS Update and the source content out of GURPS Lite, then maps each advantage, disadvantage, and skill to its 4e equivalent. Anything the GURPS Update tables don't cover is skipped (no guessed conversions).
- Audit trail. Every change (name, cost, type, IQ→Will, etc.) is shown with the verbatim rule that justified it. Click any entry in the 4e Document to jump straight to its audit entry.
- Core + expansions. Produces a Core 3e→4e base plus Magic, Transhuman Space, and WWII sections, each showing only what it adds to core 4e GURPS Lite.
- Shareable by default. Verbatim rules prose (descriptions, the magic-system text) copied from your PDFs is hidden by default so the output can be shared without redistributing that text; a toggle reveals it for personal use.
- Export. Download a standalone HTML file, or Export PDF for a print-ready document styled like a GURPS supplement (two columns, running heads, page numbers) via Paged.js.
- Everything runs in your browser. PDFs never leave your machine; there is no server and no upload.
All are free, legally downloadable from Steve Jackson Games. You provide them at runtime; they are not part of this repo.
| Purpose | File |
|---|---|
| Conversion tables (required) | GURPS Update |
| 3e source content (required) | GURPS Lite (3rd Edition) |
| 4e baseline (recommended) | GURPS Lite (Fourth Edition) |
| Expansions (optional) | Transhuman Space Lite, GURPS WWII Lite |
npm install
npm run dev # start the dev server
npm test # run the unit tests (Vitest)
npm run lint # ESLint
npm run build # type-check + production build to dist/The test suite extracts the source PDFs once into a gitignored cache; see
src/test/. PDFs themselves are never committed.
This project bundles a copy of the Paged.js polyfill
(public/paged.polyfill.js, MIT) and depends on pdf.js (Apache-2.0) and React
(MIT). Their licenses are retained in the respective files / packages.
GURPS is a trademark of Steve Jackson Games, and its rules and art are copyrighted by Steve Jackson Games. All rights are reserved by Steve Jackson Games. This game aid is an unofficial fan work, is not endorsed by Steve Jackson Games, and is released for free, non-commercial use under the permissions granted in the Steve Jackson Games Online Policy.
The source code of this project is licensed under the GNU Affero General Public License v3.0 (AGPL-3.0-only). This license applies to the converter's code only — not to GURPS, which remains the property of Steve Jackson Games.