A community and format for sharing index maps.

OpenIndexMaps use the GeoJSON Format to deliver information about an index map that references maps or other index maps. The concept of web-based index maps is not novel, however with many differing implementations, a common community-based standard was needed.


  • 1. Introduction
    • 1.1 Examples
  • 2. Common Properties
  • 3. Helpful resources
    • 3.1 Converter
    • 3.2 Tutorial

1. Introduction

OpenIndexMap is geospatial data format based on the GeoJSON Format. It consists of a GeoJSON FeatureCollection object that contains Features representing a geographic area from which additional map data exists. Features may have members which contain additional properties. These properties enable a consuming application to provide a useful finding aid for maps. OpenIndexMap defines a common set of properties that are useful as a finding aid.

OpenIndexMaps should be valid GeoJSON.

1.1 Examples

  "type": "FeatureCollection",
  "features": [
      "type": "Feature",
      "id": "mb886mv5963",
      "geometry": {
        "type": "MultiPolygon",
        "coordinates": [
              [100.0001220703126, 20.00012207031252],
              [100.0001220703126, 22.50012207031252],
              [105.0001220703126, 22.50012207031252],
              [105.0001220703126, 20.00012207031252],
              [100.0001220703126, 20.00012207031252]
      "geometry_name": "geom",
      "properties": {
        "label": "L-16",
        "recordIdentifier": "yr314gw9982",
        "websiteUrl": "",
        "iiifUrl": "",
        "thumbnailUrl": "!400,400/0/default.jpg",
        "title": "Tōa yochizu -- 東亞輿地圖 -- L-16",
        "note": "This item is really interesting."

2. Common Properties

These properties represent key and value pair members of a GeoJSON Feature represented in an OpenIndexMap. Each property (JSON key) is case sensitive and should be represented in “camel case” format.

Property Type Required? Description Example
"available" boolean no Determines whether or not this represented area is available. true
"recordIdentifier" string no An identifier for finding the item at an organization. Examples could be a unique id such as an URI, call number, or catkey. "yr314gw9982"
"downloadUrl" string no A URL in which the item can be downloaded ""
"websiteUrl" string no A URL of a website that describes or provides more information about the item. Could be a persistent url, DOI, or catalog entry. ""
"thumbnailUrl" string no A URL of an image that is a representative thumbnail of the item. "!400,400/0/default.jpg"
"iiifUrl" string no A IIIF Presentation API manifest URL for an item. ""
"label" string no A short label that represents the item within the discovery aid. Often times this can be a “sheet number” for paper maps. "L-16"
"title" string no A title for the given item. Usually longer than the label. Sometimes the label is included in this title. "Tōa yochizu -- 東亞輿地圖 -- L-16"
"note" string no Additional information that should be presented to the user "This item is really interesting."

3. Helpful Resources

3.1 Converter

A converter is available for converting shapefile index maps to OpenIndexMaps GeoJSON.

3.2 Tutorial

A Creating GeoJSON for OpenIndexMaps tutorial was created for a workshop at Geo4LibCamp 2020. The tutorial works through several examples of using QGIS to create OpenIndexMaps GeoJSON files.