Description
The browser editor on the OSM site only lets you work on a small patch at a time, stalls the moment the connection does, and gives you nowhere to start if you want to add house numbers to thirty buildings at once. JOSM takes the opposite approach: download the whole area to your machine first, do all the editing offline, then upload the result in one go.
The canvas sits over aerial imagery and you draw and drag nodes, ways and relations straight onto it. Tags are not typed by hand — the preset library is organised around real things like a restaurant, a fuel station or a pedestrian crossing, so picking one fills in the keys and values that object should carry. Before you upload, the validator sweeps the changes and lists crossing ways, unclosed building outlines and misspelled tags.
Offline editing: pull the data down, edit with the network gone if need be, and upload once at the end. Large cleanup passes no longer wait on a server between every change.
Presets and bulk tagging: common features come with ready presets that can be applied to a whole selection, and a search box finds a preset by name so you never have to remember the OSM tag spelling.
Validator: geometry and tagging problems are found before upload — self-intersecting ways, duplicate nodes, unclosed areas, changes that conflict with existing data — each listed and clickable straight to the offending object.
Many imagery layers: Bing, Esri and regional open orthophotos can be laid underneath as tracing references, and an imagery layer that sits off-register can be shifted back into alignment.
GPX tracks and photo mapping: import a track from a phone or GPS as a guide line, and geotagged photos align onto that track by timestamp, so a survey walk turns straight into usable data.
Map styles and plugins: swap the map paint style to colour features by whatever attribute you care about, and the plugin library covers bulk building generation, public transport route editing, address matching and much more.
Open source, cross platform: GPL licensed, written in Java, running on Windows, macOS and Linux.
The canvas sits over aerial imagery and you draw and drag nodes, ways and relations straight onto it. Tags are not typed by hand — the preset library is organised around real things like a restaurant, a fuel station or a pedestrian crossing, so picking one fills in the keys and values that object should carry. Before you upload, the validator sweeps the changes and lists crossing ways, unclosed building outlines and misspelled tags.
Features
Offline editing: pull the data down, edit with the network gone if need be, and upload once at the end. Large cleanup passes no longer wait on a server between every change.
Presets and bulk tagging: common features come with ready presets that can be applied to a whole selection, and a search box finds a preset by name so you never have to remember the OSM tag spelling.
Validator: geometry and tagging problems are found before upload — self-intersecting ways, duplicate nodes, unclosed areas, changes that conflict with existing data — each listed and clickable straight to the offending object.
Many imagery layers: Bing, Esri and regional open orthophotos can be laid underneath as tracing references, and an imagery layer that sits off-register can be shifted back into alignment.
GPX tracks and photo mapping: import a track from a phone or GPS as a guide line, and geotagged photos align onto that track by timestamp, so a survey walk turns straight into usable data.
Map styles and plugins: swap the map paint style to colour features by whatever attribute you care about, and the plugin library covers bulk building generation, public transport route editing, address matching and much more.
Open source, cross platform: GPL licensed, written in Java, running on Windows, macOS and Linux.
