GeoJSON Merge
Combine multiple GeoJSON files, features, or geometries into one FeatureCollection. Optionally round coordinates, renumber ids, and tag each feature by source. Runs in your browser; nothing is uploaded.
About this tool
GeoJSON Merge combines two or more GeoJSON inputs into a single RFC 7946 FeatureCollection. Paste your GeoJSON one value after another — separated by whitespace, a blank line, or one object per line (line-delimited GeoJSON / NDJSON works too) — and every feature is flattened, in order, into one collection.
Mixed input shapes are handled for you:
- A FeatureCollection contributes all of its
features. - A bare Feature is kept as-is.
- A raw geometry (
Point,LineString,Polygon,GeometryCollection, …) is wrapped into aFeaturewith emptyproperties.
Options
- Indent — spaces per level for the output; set
0to minify to a single line. - Coordinate precision — round every coordinate to N decimal places to shrink
the file (e.g.
6≈ ~0.1 m). Leave it at-1to keep full precision. - Renumber feature ids — overwrite each feature's
idwith a fresh sequential integer (0,1,2, …), fixing id collisions across sources. - Tag features with source property — name a property and each feature gets it set to its 1-based input-document number, so merged features stay traceable to the file they came from.
Everything runs locally in your browser via WebAssembly — your data is never uploaded.
Worked example
Merging a FeatureCollection with a bare point:
{"type":"FeatureCollection","features":[{"type":"Feature","properties":{"name":"A"},"geometry":{"type":"Point","coordinates":[0,0]}}]}
{"type":"Point","coordinates":[1,1]}
produces (minified):
{"type":"FeatureCollection","features":[{"type":"Feature","properties":{"name":"A"},"geometry":{"type":"Point","coordinates":[0,0]}},{"type":"Feature","properties":{},"geometry":{"type":"Point","coordinates":[1,1]}}]}
Good for
- Reassembling tiled or regional exports (per-county, per-day) into one dataset.
- Consolidating field-collected features from several files before upload.
- Cleaning up an oversized GeoJSON by trimming coordinate precision on the way in.
Limits
- Pure concatenation — it does not deduplicate features, reconcile differing property schemas, or dissolve/union overlapping geometries.
- No coordinate reprojection: GeoJSON is assumed to be WGS84 (EPSG:4326).
- Inputs must be valid JSON; a parse error reports which value (
#N) failed.
FAQ
What input formats can I paste in?
Any mix of GeoJSON FeatureCollections, bare Features, and raw geometries — concatenated with whitespace, blank lines, or one object per line (line-delimited GeoJSON / NDJSON). They're read as a stream of JSON values and merged left to right; a single value is simply reformatted.
Does it deduplicate or dissolve overlapping features?
No. This is a structural merge: every feature from every input is kept, in order. It does not remove duplicates, union geometries, or dissolve shared borders — use a full GIS tool for topology operations.
How does coordinate precision rounding work?
Set Coordinate precision to the number of decimal places you want and every
coordinate in every geometry is rounded to that many decimals — a quick way to
shrink a file (6 decimals is roughly 0.1 m at the equator). Leave it at -1 to
keep coordinates exactly as they came in.
Can I keep track of which file each feature came from?
Yes — type a property name into Tag features with source property and every
feature gets that property set to its 1-based source-document number (the first
pasted value is 1, the second 2, and so on), so you can style or filter by
origin after merging.
Is my data uploaded anywhere?
No. The merge runs entirely in your browser through WebAssembly — nothing is sent to a server, so it works offline and keeps private data private.
Developer & Automation Access
Run it from the terminal
Same engine as this page, headless — via the gizza CLI:
gizza tool geojson-merge '{"type":"FeatureCollection","features":[{"type":"Feature","properties":{"name":"A"},"geometry":{"type":"Point","coordinates":[0,0]}}]}
{"type":"Point","coordinates":[1,1]}'New to the CLI? Get gizza →
Open it by URL
Pre-fill and auto-run this tool with query parameters — the names match the API/CLI:
https://gizza.ai/tools/geojson-merge/?geojson=%7B%22type%22%3A%22FeatureCollection%22%2C%22features%22%3A%5B%7B%22type%22%3A%22Feature%22%2C%22properties%22%3A%7B%22name%22%3A%22A%22%7D%2C%22geometry%22%3A%7B%22type%22%3A%22Point%22%2C%22coordinates%22%3A%5B0%2C0%5D%7D%7D%5D%7D%0A%7B%22type%22%3A%22Point%22%2C%22coordinates%22%3A%5B1%2C1%5D%7D&indent=2&precision=-1&renumber=true&source_property=sourceMachine-readable descriptor: tool.json — title + parameters JSON Schema for agents.