Sentinel Hub
https://apps.sentinel-hub.com/eo-browser/

Maxar Open data
https://www.maxar.com/open-data

Zurich 10cm aerial imagery
https://geolion.zh.ch/geodatenservice/2122

New Zealand 10cm imagery
https://data.linz.govt.nz/set/4702-nz-aerial-imagery/

Planet:
planet.com/explorer (requires an account)
https://developers.planet.com/open/

Google Earth Engine
https://developers.google.com/earth-engine/guides