You do not need QGIS, ArcGIS or any install to open a GeoJSON file. Drop the .geojson on a free browser viewer and it draws on a map with its attribute table, ready to click, label and export. Nothing is uploaded; the file is parsed in your browser tab, and the only size limit is what that tab can hold. That is the whole answer. The rest is the step by step, the things that go wrong, and when you actually do need QGIS.

Everything below was tested on 15 September 2026 with the live viewer (static-page-tools@6016a1b from the lab); what it printed is quoted; whitespace collapsed. The test file was IBGE's 27 Brazilian states, converted with GDAL 3.13.3.

What you need

One file. That is the difference from a Shapefile.

A .geojson or a .json. The viewer decides by the suffix: a .txt with perfect GeoJSON inside is refused, and so is a .topojson, before its content is read.
Inside, any shape the spec allows: a FeatureCollection, a bare Feature, or a bare geometry such as a Point with no properties. All three opened.
Coordinates in WGS 84 longitude and latitude, in that order. If the file is in metres from a projected system, read the first thing that goes wrong below.
No .prj, no .cpg, no zip. What a Shapefile spreads across sidecars is inside the JSON or fixed by the spec.

Open it in the browser, step by step

Open the free GeoJSON viewer, the page headed GeoJSON Viewer. It parses the file in the browser, so nothing leaves your machine. The steps below are all it does.

Drop the file

Drag the file onto the zone that says Drag a GeoJSON, KML or KMZ file here, or click it and pick the file. The map zooms to the layer and the attribute table opens beside it; our 39 MB file took under two seconds. One file per drop: drag two at once and the viewer keeps the first.

Read the layers row

The layers panel is top right of the map; on a laptop-width window it starts collapsed behind a pill labelled Expand layers, so click it. One row per file: the feature count and geometry types, 27 features and 27 Polygon for our test file, a Label dropdown, and the fields, CD_UF NM_UF SIGLA_UF NM_REGIAO AREA_KM2 and 5 fields. If the count is not what you expected, the file is not what you expected.

Read the attribute table

One row per feature, one column per field, plus File and Type. Click a header to sort, use Columns to hide fields. This is the only place a GeometryCollection is named: the layers row counts it and lists no type; the table's Type column says Collection.

Click a feature

Click any shape and the Attributes panel opens with its type and every field. Pick a field in the Label dropdown and the viewer uses its value as the on-map label.

Add more files

The Add button in the layers panel opens a chooser for the next file; the map holds ten. There is no message at the limit: after the tenth file the Add button is simply gone, and the drop zone too.

Export it

The Export menu writes everything loaded as Export GeoJSON, KML or CSV. The GeoJSON is WGS 84 with full-precision coordinates, so it comes out larger: our 39 MB file exported as 46 MB. It is not a byte copy. Vertices closer than 20 cm to the line are dropped before drawing and before export: a vertex 5 cm off a straight line was gone, one 1 m off was not. And a clockwise outer ring goes out clockwise: the viewer neither rejects nor rewinds it.

The things that go wrong

Each was reproduced and dropped into the viewer.

The map draws, and it is in the wrong place

GeoJSON is WGS 84 by definition, but the 2008 draft allowed a crs member, and GDAL still writes one when you export from a projected system without asking for RFC 7946. Our file exported in UTM zone 23S carries "crs": { "type": "name", "properties": { "name": "urn:ogc:def:crs:EPSG::31983" } } and coordinates in the millions. Dropped on the viewer: no error, 27 features, and the first vertex of Acre exported back at 61.2° N, 19.5° W, in the North Atlantic between Iceland and Norway, 9,000 km from Acre. The viewer honours crs only for names its map library knows, such as the WGS 84 ones; anything else is silently taken as Web Mercator metres. Delete the crs member and it gets worse: the metres are read as degrees and the layer lands nowhere on any visible map, again with no error. The fix is upstream: ogr2ogr -f GeoJSON out.geojson in.geojson -t_srs EPSG:4326 -lco RFC7946=YES writes degrees, no crs, seven decimals. Why crs was removed, and what else RFC 7946 changed, is in the GeoJSON guide.

Unsupported file type: the suffix is wrong

A point.txt with a valid Feature inside gets Unsupported file type. Use GeoJSON (.geojson or .json). So does anything ending in .topojson. The suffix is checked before a byte is read, so rename the file. The message understates the viewer: the drop zone itself offers KML and KMZ.

Error processing file: it is not GeoJSON inside

Error processing file. Make sure it is a valid GeoJSON file. means the suffix passed and the content did not. Two files produced it in our run. A TopoJSON renamed to .json: a different format, arcs and a Topology object, that the viewer does not read; convert it first. And a crs whose type is not name, including the 2008 draft's link form: the viewer treats it as garbage, and so should you.

My styles vanished from the table

Simplestyle keys, fill, stroke, stroke-width, marker-color and the rest, are applied to the drawing and removed from the table: a feature with name, plain and seven style keys shows name plain and 2 fields in the layers row. The export writes the style back from what it drew, which is not always what came in: our polygon that also carried a marker-color came back with the marker colour as its fill.

When you actually need QGIS

The viewer reads a GeoJSON, draws it, and exports what it drew. Three things it does not do.

Reproject. It draws WGS 84 and a few known crs names; it does not transform a UTM file, and as shown above it will not tell you. ogr2ogr -t_srs EPSG:4326 does, in one line.
Validate. No right-hand rule check, no schema check: a bare geometry opens, a clockwise outer ring drew fine. A file that draws here can still be rejected by a stricter consumer.
Edit geometry at scale. Moving vertices, splitting polygons, snapping, topology rules: that is QGIS.

For a look, a count, a click and an export in another format, the viewer is enough, and faster than the install.

Test files you can use

Both URLs were requested on 15 September 2026 with a browser user agent, recording status, Accept-Ranges, the CORS header and the size. A list like this rots.

Natural Earth, 1:110m countries, on raw GitHub. is 838,726 bytes: 206 to a range request, accept-ranges: bytes, access-control-allow-origin: *. Small enough to download and drop; we have not loaded it ourselves, so read the count off the layers row. Licence: Natural Earth publishes its data as public domain.
One that is dead, so you stop looking. The old OKFN data portal path at data.okfn.org/data/datasets/geo-boundaries-world-110m/data/countries.geojson, still copied from tutorial to tutorial, does not resolve in DNS, with or without a browser user agent. The same countries are the Natural Earth file above.

The Shapefile side, four files zipped instead of one, is in how to open a Shapefile online.

For teams

Opening the file is the easy half. Someone sent you a GeoJSON because a team has to work on it: the polygons need a status, the points need photos and a form, someone reviews the field work and someone needs the report by Friday. Geodocs takes the same file onto a team map, keeps the attributes as fields the team fills in, runs the review and produces the report, map included. The viewer is where you check the file; the workspace is where it becomes work.

How to Open a GeoJSON File Online Without QGIS