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Browser GIS

GISela

A GIS in your browser: layers, attribute tables, styling, analysis and print layouts.

Launch GISela → Tutorials

GISela opens GeoJSON, KML/KMZ, GPX, CSV, TopoJSON and zipped shapefiles as map layers, converts between coordinate systems such as UTM, Swiss LV95 or the British National Grid, and lets you style them by category, by class or as a heatmap. Edit attributes with a field calculator, run buffers, overlays, dissolves, Voronoi polygons or spatial joins, measure true areas and lengths on the ellipsoid, and print a map with legend, scale bar and north arrow. Everything runs in your browser.

Free · runs in your browser · no sign-up · Version 1.0.0

GISela with a district choropleth in four orange classes, school symbols, a tram line, the layers panel and the legend

Screenshots

Features

  • Layers from your files

    Open GeoJSON, KML and KMZ, GPX, CSV with coordinates or WKT, TopoJSON and zipped shapefiles. Each file becomes a layer you can show, hide, reorder and rename.

  • Coordinate systems

    WGS 84, Web Mercator, every UTM zone, ETRS89-LAEA, Gauss–Krüger, Swiss LV95 and the British National Grid, read from .prj files and converted on import and export.

  • Attribute table

    Sort, filter and edit values in a real table, select rows to highlight features, and join columns from a CSV file by a key.

  • Field calculator

    Compute new fields with a safe expression language: arithmetic, text functions, conditions, and $area, $length or $perimeter measured on the ellipsoid.

  • Styles and choropleths

    One colour, categories, or classes by equal interval, quantile or Jenks natural breaks, with colour ramps, symbols and labels.

  • Heatmaps

    Turn points into a density surface, weighted by any number field, with an adjustable radius.

  • Buffers and overlays

    Buffer by metres, dissolve by a field, and intersect, clip, erase or unite polygon layers with GISela’s own geometry engine.

  • Spatial analysis

    Centroids, convex hulls, points in polygons, nearest neighbours, Voronoi polygons, simplification and spatial joins.

  • True measurements

    Measure distances and areas on the map, and add area, perimeter or length fields — all geodesic on the WGS84 ellipsoid.

  • Draw and edit

    Draw points, lines and polygons with snapping to existing vertices, move vertices with the mouse, or type them in a vertex list.

  • Print layouts

    Title, legend, scale bar and north arrow on A4, A3 or Letter, exported as vector PDF, SVG or PNG.

  • Export anywhere

    Save layers as GeoJSON, KML, GPX, CSV or a zipped shapefile with .prj, in the coordinate system you choose.

  • Map without seeing it

    A feature list and table describe the map in words; arrow keys step from feature to feature and a screen reader hears each one.

  • Shared workspaces

    Keep a project in a team workspace: changes sync live, and viewers can look but not edit. Without an account everything stays local.

  • Share links and project files

    Autosave with recent projects, undo and redo, .gisela.json files and share links that carry small projects inside the link.

  • API and MCP tools

    Reprojection, buffers, shapefile to GeoJSON and geodesic area and length are also tools with a JSON API for scripts and AI agents.

Templates

Start from a ready-made project and change it to fit.

Built-in tools

GISela uses these tools. Each one also has its own page and works on its own, in the browser, through the JSON API and through MCP.

  • GISela Coordinate Reprojection GISela engineConvert GeoJSON, KML, GPX, CSV or shapefiles between WGS 84, UTM, LV95, British Grid and more.
  • GISela Buffer GISela engineBuffer zones around points, lines or polygons at a distance in metres, merged or one per feature.
  • GISela Shapefile to GeoJSON GISela engineTurn a zipped shapefile (.shp, .dbf, .prj) into GeoJSON in WGS 84 or another coordinate system.
  • GISela Area & Length GISela engineTrue area, perimeter and length of polygons and lines on the WGS 84 ellipsoid, per feature.

For AI agents

GISela runs on a deterministic engine. The same functions are available as tools with a JSON API and MCP, so scripts and AI agents get exactly the results the app shows.

  • GISela Coordinate Reprojection – Convert GeoJSON, KML, GPX, CSV or shapefiles between WGS 84, UTM, LV95, British Grid and more.
    Tool page · POST https://gisela.usefulweb.app/api/v1/tools/gisela-reproject/calculate · MCP gisela_reproject
  • GISela Buffer – Buffer zones around points, lines or polygons at a distance in metres, merged or one per feature.
    Tool page · POST https://gisela.usefulweb.app/api/v1/tools/gisela-buffer/calculate · MCP gisela_buffer
  • GISela Shapefile to GeoJSON – Turn a zipped shapefile (.shp, .dbf, .prj) into GeoJSON in WGS 84 or another coordinate system.
    Tool page · POST https://gisela.usefulweb.app/api/v1/tools/gisela-shapefile-to-geojson/calculate · MCP gisela_shapefile_to_geojson
  • GISela Area & Length – True area, perimeter and length of polygons and lines on the WGS 84 ellipsoid, per feature.
    Tool page · POST https://gisela.usefulweb.app/api/v1/tools/gisela-area-length/calculate · MCP gisela_area_length

Build a project through the API, then open it in the app with a link to https://gisela.usefulweb.app/app#project=<base64url JSON>.

Import & export

Import

  • GISela project (.gisela.json)
  • GeoJSON (.geojson, .json; also the old “crs” member)
  • TopoJSON
  • KML and KMZ
  • GPX (waypoints, routes, tracks)
  • CSV with lat/lon or x/y columns or a WKT column
  • WKT (one geometry per line)
  • Zipped shapefile (.shp, .dbf, .prj, .cpg)
  • Share link (#project=)

Export

  • GISela project (.gisela.json)
  • GeoJSON
  • KML
  • GPX
  • CSV (x/y or WKT)
  • WKT
  • Zipped shapefile with .prj
  • Print layout as PDF, SVG or PNG
  • Map view as SVG or PNG
  • Attribute table as CSV

Keyboard shortcuts

Keyboard shortcuts in GISela
KeysAction
VSelect tool (click a feature)
MMeasure distance; again for area
DDraw a feature on the selected layer
Arrow keysPan the map (on the focused map); in the feature list, step to the next or previous feature
+ / -Zoom in or out
0Zoom to all layers
TOpen the attribute table of the selected layer
EnterFinish a drawing (Escape cancels it)
DeleteDelete the selected feature
Ctrl + ZUndo
Ctrl + Shift + ZRedo
Ctrl + SSave project file
Ctrl + OOpen a file
?Keyboard shortcuts (single-key shortcuts can be switched off there)

Frequently asked questions

Where is my data?

In this browser’s storage (IndexedDB) on this device. Files you open are read in the browser and never uploaded. Save a project file, export layers or back up with Bundlekeep to keep a copy.

Can my team work on the same map?

Yes, with a free account: choose File → Save to workspace… and invite people. Changes sync live; people with the viewer role can look but not edit. Without an account GISela works locally.

Which coordinate systems does GISela know?

WGS 84 and ETRS89 longitude/latitude, Web Mercator, all UTM zones (WGS 84 and ETRS89), ETRS89-LAEA Europe, the German Gauss–Krüger zones 2–5, Swiss LV95 and LV03, and the British National Grid. It reads them from .prj files and GeoJSON, and you can choose them by EPSG code.

How accurate are conversions between datums?

Projections are exact to millimetres. Changing the datum (for example OSGB 1936 or DHDN to WGS 84) uses a published 7-parameter Helmert transformation, good to about 1–5 metres. For survey work use the official grid transformations.

Why does my shapefile not open?

A shapefile is several files. Put at least the .shp, the .dbf and the .prj file into one ZIP and open the ZIP. MultiPatch (3-D) shapefiles are not supported.

How do I use the map without a mouse or without seeing it?

Tab to the feature list: arrow keys move from feature to feature, Enter selects one and the screen reader hears its name and values. The map itself pans with the arrow keys and zooms with plus and minus; drawn shapes can be typed as a vertex list.

Is there a background map with streets?

GISela shows a simple world map of country outlines (Natural Earth). It does not load map tiles from other servers; bring your own data, for example an OpenStreetMap extract converted to GeoJSON.

Limitations

What GISela does not do (yet):

  • No street or satellite basemap: the built-in background is a world map of country outlines.
  • Raster data (GeoTIFF, images) and 3-D data are not supported; Z and M values are dropped.
  • Overlays work on longitude/latitude like a desktop GIS on an EPSG:4326 layer; buffers and distances use a local metric plane.
  • Datum shifts use Helmert parameters (about 1–5 m), not national grid files such as OSTN15 or BeTA2007.
  • Coordinate systems outside the built-in list cannot be read or written.
  • Large datasets (more than 50,000 features per layer) are not supported, and drawing slows down above a few thousand complex features.
  • No geocoding (address search); place data comes from your files.

Tutorials

Learn GISela step by step.

  1. Your first map in five minutesOpen a GISela template, find your way around layers, legend and map, select features with the mouse or the keyboard and keep your project in this browser or in a file.Beginner 5 min
  2. Import data and choose coordinate systemsAdd GeoJSON, shapefiles, KML, GPX, CSV, WKT and TopoJSON to a map, read CSV files with Swiss or UTM coordinates, and show coordinates in the system you work with.Beginner 8 min
  3. Styles, classes, labels and heatmapsColour features by category or in classes (equal interval, quantile, natural breaks), choose symbols and labels, and show many points as a heatmap.Intermediate 7 min
  4. Attribute table, filters and the field calculatorSort and edit attributes, filter features with expressions, compute new fields such as density, and join a CSV table by a key.Intermediate 8 min
  5. Buffers, overlays and spatial analysisDraw buffer zones, intersect and clip layers, count points in polygons, find nearest neighbours, make Voronoi polygons, simplify lines and join by location.Advanced 10 min
  6. Measure, print, export and shareMeasure distances and areas on the ellipsoid, make a print layout as PDF, SVG or PNG, export layers as shapefile, GeoJSON, KML, GPX or CSV, and share a project by link or in a workspace.Beginner 8 min

Ready to try it?

Launch GISela →

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