Universal workbench

GeoJSON to TopoJSON

Convert GeoJSON to TopoJSON locally with explicit source and target coordinate reference systems.

Device-onlyNo uploads. Ever.

Pipelines, branches, presets, naming, and detailed controls

Display

Text sizeDensity High contrast Monospace editor

Quick start

JSON → YAML WebP → PNG SVG → React JSX Plain text → Base64

From

Help me choose the best output Suggested: Coordinate CSV

What matters most?

Recommendations use the registered target format and tested fidelity classification. They never inspect or upload your content.

01Input

Drop files or a folder hereChoose GeoJSON files or a folder — batch input is welcome

Choose files Choose folder

or paste content

02Configure & run

GeoJSONTopoJSON

structural conversion · single or batch

Conversion preflightSize, memory, engine, execution, and fidelity before you start

Input: 152 B
Estimated peak memory: 16 MiB
On-demand download: No large engine download
Execution: Responsive local worker
Fidelity: No lossy step declared

What to providePaste valid GeoJSON syntax or drop one or more .geojson / .json files.What you’ll getProduces previewable TopoJSON text and a correctly named download.

Source CRSCoordinate system of the input, such as EPSG:4326 or EPSG:3857. A .prj embedded in a Shapefile is read by the importer before this optional transformation.Target CRSCoordinate system written to the output. Use EPSG:4326 for standard GeoJSON and TopoJSON interoperability.TopoJSON quantizationTopology coordinate grid size. Higher values retain more positional precision.100000

Output naming & batch behavior

Filename templateAvailable variables: {output} (converter’s meaningful name), {name}, {target}, {ext}, {index}. Duplicate names receive a safe numeric suffix.

Exampleoutput.topojson

Pipeline 1 linear · 0 branches

Why use A → B → C?

A pipeline feeds each result directly into the next compatible converter. Use one when the destination needs an intermediate representation or when you want to inspect and normalize that middle format.

JSON → CSV → XLSX turns records into rows before building a workbook.
Markdown → HTML → DOCX resolves markup before creating a document.
SVG → PNG → PDF intentionally flattens vector artwork before placing it on a page.

Only type-compatible next steps are offered. Lossy steps are marked before you run them.

1GeoJSON to TopoJSONstructural

Add compatible step

Parallel output branchesEach branch receives the final linear result. Branches do not feed or depend on one another.

Add a parallel destination

Processing happens locally. Your file bytes are never sent anywhere.

About this conversion

How to convert GeoJSON to TopoJSON

Before you start

Paste valid GeoJSON syntax or drop one or more .geojson / .json files.

Accepted: .geojson, .json · application/geo+json

Paste valid GeoJSON content, choose files, or drag them onto the drop zone.
Confirm the detected format and adjust the available settings. Mixed-format batches are flagged before conversion.
Select “Convert on this device.” Produces previewable TopoJSON text and a correctly named download.

How this converter behaves

Features and coordinates are parsed locally, transformed only with the explicitly selected CRS, and serialized into the requested geospatial representation.

What happens to your data?

The conversion engine runs in this browser tab. OmniCastConverter has no upload API and never sends your content, file name, or converted result to a server.

Fidelity and limitations

This route is classified as structural. The converter preserves meaning and structure supported by both formats.

Shapefile field names and property types are constrained by DBF. TopoJSON quantization can slightly change coordinates.
Geometry is reprojected only when source and target CRS differ; verify axis order and units for custom definitions.

Try a valid example

The “Use example” action in the workbench loads this exact input. Produces previewable TopoJSON text and a correctly named download.

{"type":"FeatureCollection","features":[{"type":"Feature","geometry":{"type":"Point","coordinates":[25.2797,54.6872]},"properties":{"name":"Vilnius"}}]}