Skip to content

3. Context and Scope

3.1 Business Context

Tanker24 is a web application designed for German car drivers to check real-time fuel prices at gas stations in their vicinity and track their fuel expenditures over time. Gas prices in Germany are regulated by the Market Transparency Unit for Fuels (MTS-K), which publishes prices via a registration-only API. Tanker24 integrates with the Tankerkönig API — a free, community-driven service that proxies the MTS-K data — to provide up-to-date station and price information.

The application fills a gap in the market for a free, privacy-respecting fuel price comparison tool that also offers personal expenditure tracking. Unlike commercial alternatives, Tanker24 requires no payment, no third-party analytics, and gives users full control over their expendature data via JSON (nested-data) and CSV (flat-data) export.

3.2 System Scope

The system context and scope is described with a C4-Model System Context (Level 1) diagram. It displays all interacting partners at a high level while specifying the required interfaces to users and external systems.

In scope (Tanker24):
- User authentication and registration (invitation-key based)
- Search for gas stations by geographic coordinates
- Display of fuel prices (Diesel, E5, E10) sorted by price
- Tracking fuel filling events for multiple cars
- Export of user data (fueling history, cars) as JSON and CSV

Out of scope:
- Payment processing for fuel purchases
- Navigation/routing to gas stations
- Native mobile applications (Android/iOS)
- Integration with vehicle telemetry systems
- Administrative dashboard for user management
- Geocoding (address-to-coordinate conversion)

3.3 System Context Diagram (C4-Model Level 1)

«person»User German car driver«system»Tanker24 Web system for checkinggas prices in the users area.«external_system»Tankerkönig Free data provider for gasprice data based on theBundeskartelamt API.«external_system»OpenStreetMap Free map data provider forvisualisation.Request gas prices forarea.[Web Interface]Save filling history.[Web Interface]Request gas price Data[REST]Request map data[REST]
«person»User German car driver«system»Tanker24 Web system for checkinggas prices in the users area.«external_system»Tankerkönig Free data provider for gasprice data based on theBundeskartelamt API.«external_system»OpenStreetMap Free map data provider forvisualisation.Request gas prices forarea.[Web Interface]Save filling history.[Web Interface]Request gas price Data[REST]Request map data[REST]

System Context Diagram

3.4 External Interface Summary

Interface Provider Direction Protocol Data
Tanker24 Web UI User → Tanker24 Inbound HTTPS User requests, form submissions
Tankerkönig API Tanker24 → Tankerkönig Outbound REST/JSON Gas station lists, prices, opening times
OpenStreetMap Tiles Tanker24 → OSM Outbound HTTPS Raster map tiles (light/dark)