Detect Vandalism

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Main article: Vandalism

Vandalism is intentionally ignoring the consensus norms of the OpenStreetMap community about editing data. Simple mistakes and editing errors are not vandalism but may need to be reverted using some of the same tools that are used for vandalism.


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: