Detect Vandalism

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Resources available now

See Feeds (map editing), Monitoring Tools and QA tools in general.

Online Services


  • - An OSM "weirdness" detector: Reads minutely/hourly diffs and looks for oddly-shaped ways or ways that don't quite make sense.
  • osm-weirdness - a tool to find weird changesets
  • OSMCha - Python package to detect suspicious OSM changesets
  • OSM Hall Monitor - Suite of Python tools: reads diff files looking for large edits, skewed ratios of deletions to total edits or modifications to total edits, or changesets with modifications across the map; also can watch specific users or objects, with notification available; smart geospatial comparison coming soon (objects of certain shapes, etc.).
  • OpenStreetMap Analytic Difference Engine.

Possible other resources

Possible libraries/algorithms to use


Important: none of the below criteria alone means anything. But combined it may be worth a look...

  • new user
  • user name changes versus id
  • number of edits
  • number of changesets
  • area of changesets
  • lots of special actions like
  • renaming
  • reclassification
  • edits spread over a wide area
  • lots of deletions
  • movement of data over a long distance
  • high version numbers of objects (edit war)
  • operating times (bots?)
  • waylength above threshold
  • way node reduction
  • number of unique/similar changeset names


A periodically generated report could list possible

  • changesets
  • users
  • areas

to be inspected closer. It could even introduce a scoring system.


  • I'm dreaming of a tool that could warn you by email of any change made on a object you modified in the past which has defined properties.
  • having the word "survey" in the note tag
  • having a note, or a fixme, or a source tag
  • in a zone of interest
  • deleted object
  • moved object
  • ...



Examples of vandalism and mapping accidents: