Boundr

Find all UK administrative boundaries that geographically contain a coordinate point.

Use this to answer "what county/borough/ward is this location in?" for a latitude/longitude. Returns lightweight metadata only — no geometry. If you need to display a boundary shape, call get_boundary_geojson_by_code() with the returned code.

Multiple boundaries at different administrative levels typically contain the same point (e.g. a ward, a borough, and a county). Filter by boundary_types to restrict which levels are returned.

Call list_boundary_type_codes() first if you are unsure which type codes to use.

Get the bounding box and centroid for a boundary by its ONS census code.

Returns min_lat, max_lat, min_lng, max_lng, centroid_lat, centroid_lng. Pass the bbox values directly to Knotsure's sightings_in_bbox() or geographic_summary(). Much cheaper than get_boundary_geojson_by_code() for spatial queries because no geometry is fetched or serialised.

Look up metadata for a single UK boundary by its ONS census code. No geometry.

Use this when you already have a census code (e.g. from search_boundaries_by_name() or find_boundaries_at_point()) and need structured metadata such as area size or type label. If you also need the boundary shape for display or analysis, call get_boundary_geojson_by_code() instead.

ONS census codes (sometimes called GSS codes or LAU codes) are stable identifiers of the form "E09000012" (Hackney), "E10000016" (Kent), etc. The first letter indicates the country: E = England, W = Wales, S = Scotland, N = Northern Ireland.

Fetch the full GeoJSON geometry for a UK boundary by its ONS census code.

Returns a GeoJSON Feature object (WGS-84 / EPSG:4326) suitable for rendering on a map or performing geometric analysis. The geometry can be large — county and ceremonial county polygons are especially heavy. Only call this when you specifically need the shape; for metadata only use get_boundary_by_code() instead.

IMPORTANT — Leaflet / web maps: use get_boundary_geojson_simplified() instead. The full geometry is large enough to exhaust your context window before you can finish writing the page. The simplified version is safe to embed directly in HTML and indistinguishable from the full shape at normal map zoom levels.

Use this tool only when you need full-fidelity geometry for server-side analysis (e.g. precise point-in-polygon checks, area calculations, clipping).

Obtain the census code from search_boundaries_by_name() or find_boundaries_at_point() before calling this.

Fetch simplified GeoJSON for a boundary by its ONS census code.

Safe to embed directly in generated HTML map files. At the default tolerance (0.0001°) a constituency polygon shrinks from ~4,000 vertices to ~200–400 with no visible difference at normal map zoom levels.

Prefer this over get_boundary_geojson_by_code() when writing Leaflet map pages — the full geometry is large enough to exhaust your context window before you can finish writing the HTML.

Returns every valid UK boundary type code mapped to its human-readable label.

Call this before using any tool that accepts a boundary_type or boundary_types argument so you know which codes are legal. Passing an unlisted code to another tool raises a ValueError.

Boundary type codes are stable Ordnance Survey identifiers. Common ones:

• "CTY" → County

• "LBO" → London Borough

• "UTA" → Unitary Authority

• "MTD" → Metropolitan District

• "DIS" → District

• "DIW" → District Ward

• "CCTY" → Ceremonial County

• "HCTY" → Historic County

• "WMC" → Westminster Parliamentary Constituency

• "GLC" → Greater London Constituency

• "SWC" → Scotland/Wales Constituency

• "PAR" → Parish

• "CED" → County Electoral Division

Returns: Dict mapping code → label for all supported boundary types, e.g. {"CTY": "County", "LBO": "London Borough", ...}

Search for UK administrative boundaries by name (case-insensitive partial match).

Use this to discover boundaries when you have a place name but not a code. Returns lightweight metadata only — no geometry. If you need to display or analyse the boundary shape, call get_boundary_geojson_by_code() with the returned code.

Call list_boundary_type_codes() first if you need to filter by type and are unsure which code to use.