I want to do a web project with OpenLayers 4 to show what I´ve learn at work about web mapping and OL4 (at work we use mapserver with PostgresSQL) but I want to do something basic and with a static website, no backend.
Anyone know of some API that offers WMS, WMTS or TILE for free compatible with OpenLayers 4?
I've found some articles but out of date, in my search, I found this 2 company that seems offers the product I need:
https://www.ordnancesurvey.co.uk/business-and-government/products/os-openspace/api/
But I don´t understand if they are OL compatible and if they are totally free.
Some advice?