GameDev Toolbox
Free tools for indie game developers.
GameDev Toolbox is a static website of browser-based utilities for designing and balancing games. Everything runs locally in the browser: no backend, no database, no accounts, no analytics and no uploads. It is supported by one small banner ad per page, isolated from the tools (see Ads).
Live site: https://gamedev-toolbox.freewebtoolss.workers.dev/
Tools
RPG Stat & Balance Generator (/tools/rpg-stat-generator/)
Generates HP, Attack, Defense and Speed for RPG characters and enemies across a level range.
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Starting and maximum level (0 to 9,999, up to 10,000 rows)
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Base value and growth per level for each stat
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Growth types, where n is the number of levels gained since the starting level:
| Type | Formula |
|---|
| Linear | base + growth × n |
| Percentage | base × (1 + growth% × n) (a share of the base value, not compounding) |
| Exponential | base × (1 + growth%)^n (compounding) |
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Optional level scaling: multiplies every stat by (1 + boost%)^k, where k is the number of milestone levels (multiples of N) passed since the starting level
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Rounding: nearest, down, up, 1 or 2 decimal places (applied last)
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Summary tiles, an Attack-versus-Defense balance check, and one small chart per stat, with pointer and keyboard readouts
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Table filters (25, 10-20, 1, 10-20, 50) and an every-Nth-level view
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Copy (tab-separated), Download CSV, Download JSON; exports always contain every generated level
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Specific validation messages per field, including the exact level where a stat overflows or drops below zero
More tools are listed as "Coming later" on /tools/ and are not built yet.
Project structure
public/ Everything Cloudflare serves (the Wrangler assets directory)
index.html Home
tools/index.html Tools list
tools/rpg-stat-generator/ The generator page
about/index.html About and privacy
404.html Served for unknown paths
_headers Security headers, including the Content-Security-Policy
robots.txt, sitemap.xml, favicon.svg, favicon.ico, apple-touch-icon.png
assets/css/styles.css All styles; light and dark themes
assets/js/theme.js Theme toggle (the only thing saved, in localStorage)
assets/js/rpg-stats-core.js Pure calculation, validation and export logic
assets/js/rpg-stat-generator.js Page wiring for the generator
assets/js/stat-chart.js Dependency-free SVG charts
assets/js/ads-config.js Adsterra banner key (empty = ads off)
assets/js/ads.js Places the sandboxed ad frame in the page's ad slot
ads/banner.html, banner.js The ad frame document that runs Adsterra's code
assets/img/og-image.png Social preview image
tests/ Unit tests for the calculation core and the ad settings
wrangler.jsonc Cloudflare Workers static assets configuration
There is no build step and there are no npm dependencies. Pages are plain HTML; each one carries its own copy of the header and footer.
Development
Requires Node.js 20 or newer.
npx wrangler dev
Opens the site at http://localhost:8787 with the same routing and headers as production.
node --test
Runs the unit tests for the calculation core. They also check that the form defaults in the HTML match the defaults in rpg-stats-core.js.
Deployment
The site deploys to Cloudflare Workers as static assets (wrangler.jsonc points assets.directory at ./public; there is no Worker script).
npx wrangler login
npx wrangler deploy
html_handling: auto-trailing-slash serves /tools/ from tools/index.html and redirects /about to /about/. not_found_handling: 404-page serves 404.html with a 404 status.
If the site moves to a custom domain, replace https://gamedev-toolbox.freewebtoolss.workers.dev in the HTML files, robots.txt and sitemap.xml.
Privacy
All calculations run in the browser. The _headers file sends the pages a Content-Security-Policy with connect-src 'none', so they cannot make fetch, XHR, WebSocket or beacon requests even by mistake. The only value the site stores is the light/dark theme choice, kept in the browser's localStorage. Ads run in a separate sandboxed frame (below) and cannot see any of this.
Adding a tool
- Create
public/tools/<tool-slug>/index.html, copying the header, footer and <head> pattern from an existing page (update the title, description, canonical and Open Graph URLs).
- Put calculation logic in its own pure module under
public/assets/js/ and cover it with tests in tests/.
- Move the tool's card on
public/tools/index.html from "Coming later" to "Available now".
- Add the page to
public/sitemap.xml.
Ads
Each page has one small 320 × 50 Adsterra banner: under the Settings panel on the generator page on desktop, and at the bottom of the page on phones and on the other pages. The 404 page has none.
Turning ads on. Ads are off while key in public/assets/js/ads-config.js is empty; nothing is requested from Adsterra and the slots stay collapsed. Create a 320 × 50 Banner unit in an Adsterra publisher account, then copy its key and script host from the unit's code into that file (the comments there show where each value comes from), run node --test, and deploy.
How the ad is isolated. assets/js/ads.js loads /ads/banner in an iframe with sandbox="allow-scripts allow-popups allow-popups-to-escape-sandbox" and no allow-same-origin. The frame gets an opaque origin, so ad code cannot read the page, the values typed into it, the site's storage or cookies, and cannot redirect the page; clicks open the advertiser in a new tab. Only /ads/* gets a relaxed Content-Security-Policy in _headers; the pages keep connect-src 'none' and only gain frame-src 'self'.
No empty boxes. A slot shows only after the frame reports that an ad rendered. If nothing renders within a few seconds (no fill, an ad blocker, a network error), the frame is removed and the slot collapses. The "Advertisement" label appears only alongside a real ad.
Visitors in the EU and UK may need to give consent before an ad network sets cookies. Check Adsterra's current requirements before relying on ad revenue from those regions.
