WMS, WMTS and WFS Viewer

The fastest way is to ask the service to describe itself: append `?SERVICE=WMS&REQUEST=GetCapabilities` (or point at the WMTS `.xml`) and check whether the answer is a real XML document — not an HTML error page dressed up as a 200 OK. Paste that same address above: this tool runs that check for you, shows how many seconds the service took to answer, lists the available layers as a tree, and names exactly which of four things went wrong when it doesn't work — a bad address, a server that's down, a timeout, or a response that isn't OGC at all. It's the same question `curl` answers in a terminal, tested the way a browser actually tests it — which isn't always the same thing (next section).

Here's the trap nobody warns you about: a WMS that works fine in QGIS can be completely unusable on a web page, because QGIS doesn't care about CORS (Cross-Origin Resource Sharing) and a browser does — and there's no frontend fix for that, only a server-side proxy, which is exactly what Geodocs runs behind the scenes. Two things break differently: an `http://` address on an `https://` page is blocked before any request even leaves — "mixed content" — and no proxy fixes that, only the service itself enabling HTTPS. CORS, on the other hand, blocks specifically the requests that fetch data — capabilities, WFS, clicking to identify a point — while the map tiles keep loading fine, because an `<img>` tag never asked anyone's permission. We manually tested eight well-known public services: six passed CORS, two didn't (mundialis and Brazil's IBGE) — don't expect every address on the internet to work here.

The capabilities document describes layers as a tree, not a list — literally: a service can group related layers under a parent `<Layer>` that has no `<Name>` at all, existing only to organize its children visually (that's why you'll see "(group)" instead of a real name). Turning on a whole group activates everything inside it; turning on a single leaf switches on just that layer. Not every layer accepts a click: the `queryable` attribute decides whether that spot on the map can be interrogated with `GetFeatureInfo`, and purely decorative layers — an outline, a grid — are usually marked not queryable. The tree you see here is the same hierarchy the server published, nothing flattened — that's what makes a group show up as a group instead of disappearing.

A WMS hands you a picture of the map — pixels, no geometry, no attributes, great for looking at or printing, useless if you need to sum areas or filter by an attribute value. WFS solves exactly that: it returns real vector features — geometry plus every column the service publishes — in the same format every other viewer on this site already uses, so you can open the attribute table, click a feature on the map and see its data as if it were a GeoJSON file you'd loaded locally. The trade-off is speed for completeness: a WFS layer with hundreds of thousands of features takes longer to answer and this tool caps how many it pulls at once — but every one of them carries real data, not just a coloured pixel.

We tested over 60 public WMS, WMTS and XYZ endpoints — satellite imagery, topographic basemaps, government reference data — and recorded the status code, the response time, and whether each one actually works from a browser (not just from `curl`). The full guide, with the URL, layers and projection for each service, is at https://geodocs.io/en/blog/free-wms-wmts-basemap-urls-2026 — paste any of those URLs above to explore its layers before you wire it into your project.