Skip to content

ADR 007: Choosing OpenStreetMap Standard Raster Tile Provider

Date: 2026-03-25
Context: Mapping and Geospatial Services
Status: Currently accepted

1. Context

Our project requires a reliable raster tile provider for rendering OpenStreetMap data on interactive maps. Having chosen OpenStreetMap as the data source (ADR-006), we now need to select which tile server to use. The key requirements include:

  • Standard OSM Carto styling matching openstreetmap.org
  • No API key requirements
  • No usage-based billing
  • Global coverage with consistent quality
  • Support for standard {z}/{x}/{y} tile coordinates

We evaluated several raster tile providers based on OpenStreetMap data.

2. Decision

We decided to use the OpenStreetMap Standard tile layer (https://tile.openstreetmap.org/{z}/{x}/{y}.png) as our primary raster tile provider.

3. Rationale

Benefits of using OpenStreetMap Standard:

  • Official Standard Layer:
    • Matches the openstreetmap.org front page appearance
    • Most widely recognized OSM visual style
    • Consistent with user expectations
  • Free and Open:
    • No API key required
    • Free for use following the OSM tile usage policy
    • Funded by donations, no commercial interests
  • Global Coverage:
    • Same comprehensive global coverage as OSM data itself
    • Consistent quality across all regions
    • Regular updates with OSM data changes
  • Technical Reliability:
    • CDN-backed infrastructure with multiple subdomains (a, b, c)
    • IPv6 support enabled
    • Well-documented and stable API
  • No Vendor Lock-in:
    • Multiple fallback tile servers available
    • Easy to switch providers if needed

Alternatives considered:

Option Pros Cons
OpenStreetMap.de German/local language labels, free Restricted commercial use, German-focused styling
OpenStreetMap.fr French labels, some enhanced features, HTTPS/HTTP2 French-focused labels may not suit all use cases
Humanitarian (HOT) High contrast, disaster relief focused Different visual style, not standard appearance
CyclOSM Cycling-focused, bicycle routes highlighted Not general-purpose, specialized styling
Carto (Positron/Dark Matter) Clean minimal design, dark mode option Commercial service, requires attribution, registration
MapTiler Multiple styles, professional quality Commercial pricing, requires API key registration
Stadia Maps (Alidade Smooth) Modern styling, free tier available Commercial service, no registration required for dev

The German and French variants were not chosen as they localize labels to specific languages, which may not match user expectations for a general-purpose application.

Carto, MapTiler, and Stadia Maps are commercial services that, while offering quality tiles, introduce vendor dependencies and potential costs at scale.

The Humanitarian style and CyclOSM have specialized visual designs better suited for specific use cases rather than general mapping.

OpenStreetMap Standard provides the familiar, neutral appearance that best serves our application's general-purpose mapping needs.

4. Consequences

Positive Outcomes

  • Consistent map appearance matching the OSM website users know
  • No API costs or registration requirements
  • Full compliance with OSM licensing (attribution required)
  • Easy integration with Leaflet, MapLibre, and OpenLayers
  • Multiple fallback options if the standard server is unavailable

Tradeoffs and Considerations

  • Fair usage policy limits apply (see OSM Tile Usage Policy)
  • High-traffic applications may need to run their own tile server
  • Update latency varies (1 minute to 1 day depending on zoom level)
  • Limited customization compared to commercial alternatives
  • Must display proper OSM attribution on maps

5. Extending to Dark Theme

5.1 Context

Our application requires both light and dark theme map options to match user interface preferences. The dark theme is particularly important for: - Night-time usage - Reducing eye strain in low-light environments - Aesthetic consistency with dark-mode UI designs

5.2 Decision

We decided to use CartoDB Dark Matter (https://basemaps.cartocdn.com/dark_all/{z}/{x}/{y}.png) as our dark theme tile provider.

5.3 Rationale

  • High-Quality Dark Design:
  • Clean, minimal dark basemap with excellent contrast
  • Subtle colors optimized for dark backgrounds
  • Well-balanced label readability on dark tiles
  • No Authentication Required:
  • Free to use with attribution
  • No API key or registration needed
  • Same free tier as standard Carto tiles
  • Consistent API Structure:
  • Same {z}/{x}/{y} coordinate format as standard tiles
  • Easy to swap between light and dark themes in code
  • Both use HTTPS endpoints
  • Technical Reliability:
  • CDN-backed with global distribution
  • Stable, well-maintained service
  • Regular updates matching OSM data

Alternatives Considered

Option Pros Cons
Stadia Maps Alidade Smooth Dark Modern styling, free tier available Commercial service, requires attribution
MapTiler Dark Professional quality, multiple styles Commercial pricing, requires API key
OSM Bright (self-hosted) Full control, customizable Requires self-hosting infrastructure
Humanitarian Dark High contrast Not a standard dark theme option

Stadia Maps was considered but requires commercial terms and attribution that differs from our preference for more permissive usage.

MapTiler offers excellent dark styles but requires API key registration and has usage-based pricing at scale.

The CartoDB Dark Matter layer provides the best balance of quality, accessibility, and ease of integration for our dark theme needs.

5.4 Consequences

Positive Outcomes

  • Dark theme available for night-time and low-light usage
  • Maintains consistent tile API format across themes
  • No additional costs or registration requirements
  • Easy to implement theme switching in the UI

Tradeoffs and Considerations

  • CartoDB is a commercial service (recently acquired by MapTiler); terms may change
  • Attribution required: "© OpenStreetMap contributors © CARTO"
  • Dark theme has slightly different coverage than standard OSM (same data source)
  • Consider implementing theme detection based on system preferences

6. References