Who builds Sourcemap Explorer
Sourcemap Explorer is a browser extension built and maintained by Mapree, a one-person studio focused on devtools that respect both your time and your data. There is no company behind the page — just a developer who got tired of every “tech stack detector” either being a paid SaaS, missing the modern frontend completely, or quietly shipping the URL of every site you visit to a server.
Why this exists
Most browser-based detection tools work the same way: they fingerprint a page, send the result home, and surface a tidy badge in your toolbar. That model is fine for sales prospecting and competitive intelligence. It is not great when you are reverse-engineering a UI for legitimate reasons — debugging a regression, auditing a third-party widget, learning how a particular animation was built — because the tool you reach for is also a side-channel.
Source maps are a richer signal than fingerprints, and they sit right there in the page. If a build was shipped with sourcemaps enabled (or with one of the now-common “hidden” sourcemap URLs), you can rebuild the original project tree, see the actual file names, and read code the way the author wrote it. Sourcemap Explorer does that locally, without sending the URL anywhere, and then layers a Wappalyzer-grade tech detection on top so you also get the framework, the libraries, the WordPress plugins, and the npm packages that powered the page.
What the project values
- Local-first.Detection, parsing, and the entire decompile pipeline run inside the extension. No backend, no telemetry, no “anonymous usage stats.” If the network tab in DevTools shows a request you didn’t initiate, that is a bug.
- Honest comparisons. The /alternatives section is allowed to say that other tools win at certain jobs (Wappalyzer’s breadth, BuiltWith’s sales-team data, W3Techs’ market share). The product is not for every workflow.
- Free and unmonetised at the user surface.The extension itself has no paid tier, no “Pro” gate, no registration. The landing pages run AdSense to keep the project sustainable, but the tool you actually use is unaffected.
- Documentation as a first-class citizen. Every technology we can detect has its own page under /detect explaining the signals we look at and how to verify them yourself. Every common “how do I figure out X” lives in /how-to.
How it’s built
The extension is a Manifest V3 WebExtension written in TypeScript and bundled with Vite. The detection pipeline reuses the Wappalyzer fingerprint database (vendored, indexed at build time) plus a sourcemap-aware scanner that recognises npm packages by file path and decompiled module signature. The decompile side runs Babel and a custom set of identity-aware passes inside an offscreen document, so the popup stays responsive even on large bundles.
The landing site you are reading is a Next.js 16 app rendered to static HTML for almost every route. Content is hand-written; the stack catalogue and the per-package pages are template-driven on top of vendor data (Wappalyzer, the npm registry, wordpress.org). Source for both the extension and the site lives in the same monorepo on a self-hosted Gitea.
Get in touch
The fastest way to reach me is the contact form on the homepage or by email at mapree@mapree.dev. Bug reports, “you cannot detect this site” reports, corrections to a /detect page, and feature suggestions are all welcome. Replies typically land within 48 hours.
Legal & compliance
Sourcemap Explorer reads only what your browser is already loading. It does not bypass authentication, scrape behind paywalls, or interact with sites in any way the host has not already permitted your browser to do. The privacy policy and the terms of use spell out the formal details: what is collected (very little), what is stored (less), and what you agree to by using the tool.