Terraster pulls exclusively from free sources whose terms permit commercial use:
mostly public domain or attribution-only, plus OpenStreetMap data that is share-alike on
the database while the images you export need only a credit. No source needs a key,
a licence purchase, or an account.
Terrain elevation & surface normals
AWS Mapzen Terrain Tiles — hosted under the AWS Open Data Sponsorship program.
Underlying data is a mosaic of NASA SRTM, USGS NED, NGA GMTED2010, NOAA ETOPO1, and
others — all US federal / international public-domain sources.
Attribution required: Elevation data © Mapzen (SRTM / NED / GMTED / ETOPO1)
Satellite imagery & environmental layers
NASA GIBS — US Government public-domain imagery (VIIRS, MODIS, IMERG rainfall,
NDVI vegetation, aerosols, night lights, land surface temperature, snow cover, and more).
No API key, no attribution legally required. Native resolution ~250m.
Credit appreciated: Imagery courtesy NASA/GIBS
EOX Sentinel-2 cloudless — the default source in the Satellite Photography
palette. Cloud-free global mosaic of ESA Sentinel-2
imagery at ~10m native resolution (up to zoom 14). Free under CC BY 4.0.
Attribution required when used: Sentinel-2 cloudless — s2maps.eu by EOX IT Services GmbH · Contains modified Copernicus Sentinel data 2020 · CC BY 4.0
Map picker basemaps
The map you draw your region on. These tiles are only ever displayed there — none of
them is composited into your artwork or baked into an export. The NASA Satellite option
is GIBS imagery, covered above.
OpenTopoMap — topographic style rendered from OSM + SRTM contours. The default.
Attribution required: © OpenTopoMap (CC-BY-SA), © OpenStreetMap contributors
OpenStreetMap vector data
OpenFreeMap — pre-built vector tiles, read by four palettes: OSM Map,
which draws a label-free basemap from them in your browser; Buildings, which extrudes
the footprints into 2.5D massing; Roads; and the coastline option in
Bathymetry. No key, no rate limit, and explicitly free for commercial use.
The tiles follow the OpenMapTiles schema and the data underneath is
OpenStreetMap, so the licence is still ODbL 1.0 — share-alike on the
data. An image you export counts as a "Produced Work" and needs only the credit
below; redistributing or building on the underlying data can trigger share-alike.
Attribution required when used: © OpenStreetMap contributors (ODbL) · © OpenMapTiles · OpenFreeMap
Heights are crowd-sourced, and often a default. The tiles carry a
render_height that OpenMapTiles derives from an OSM height or
building:levels tag — but where a building has neither, it falls back to a flat
3 m. Well-mapped city centres come through almost fully measured; elsewhere whole
neighbourhoods render at that uniform invented height. The status line reports what share of
a fetch carried a genuinely measured height. Treat the massing as illustrative, never as
survey data.
Two quirks of tiled data worth knowing. Buildings that share attributes are merged
by the tiler into single multi-part shapes, and buildings straddling a tile border arrive cut
in two — the renderer detects those cuts so outlines aren't drawn along them. Geometry is
also simplified for tile delivery, so footprints are slightly coarser than raw OSM.
Location search
Photon (Komoot) — free geocoder built on OpenStreetMap data. Not a paid service;
heavy production traffic should self-host.
Attribution required: Search © OpenStreetMap contributors (via Photon)
What gets baked into your PNGs
The Output palette's Attribution toggle (on by default) burns a small credit
strip into the bottom of each exported image, listing only the sources actually used in
that composite. If you're licensing separately or embedding the export somewhere you'll
handle attribution yourself, you can turn it off.
Bear in mind that for some sources — Sentinel-2, and the OpenStreetMap data behind the
OSM Map, Buildings and Roads layers — attribution is a licence condition rather than a courtesy.
Switching the strip off is fine, but the obligation to credit them moves to you.