All OGC WMTS tiles from map.geo.admin.ch are available in Webmercator projection! Yes, this really means you can now use the swiss national maps and all GeoAdmin API layers in your favorite library without reprojection1! Beside the LV03 (EPSG:21781), the following WMTS tilematrix sets are offered:
Plate-Carrée WGS1984 (EPSG:4326)
Plate-Carrée ETRS89 (EPSG:4258)
WGS84/Pseudo-Mercator (EPSG:3857, as used in OpenStreetMap, Bing, Google Map)
The same condition apply to the native tiles: you have to register within swisstopo web access - WMTS to gain access to these services.
Note: These tiles are reprojected on-the-fly with MapProxy, so be nice not destroying the servers by requesting too many tiles.
Unpolished examples to tests the compatiblity with popular JS web-mapping libraries.
Very few web mapping frameworks are able to parse the GetCapabilities document and configure a new layer with it. The old Openlayers 2 is one of them.
An another Openlayers 3 example, with OSM OpenSnowMap.org, again to check the WMTS tiles alignement.
ArcGIS for JS (ESRI)
Bing Map (Microsoft)
Яндекс API Карт
Also work in Desktop Client QGis 2+ and ESRI ArcGIS2 10.2+