Why this tool is useful
Record a trustworthy map extent for indexing, previews or storage checks without opening the dataset in a remote map service or exposing its properties.
Local File Tools · runs locally
Private GeoJSON Bounding Box Calculator and Writer
Calculate the two-dimensional extent of every valid GeoJSON position and download a normalized FeatureCollection with an RFC-compatible top-level bbox, locally.
Ready. Your working data stays in this browser.
Files and capture streams stay on this device. Processing uses browser APIs only; nothing is uploaded to YTSave, the media API or a proxy. No server copy is created, stored or left to delete. The file picker is cleared when processing starts, and disposable worker memory is destroyed after completion or cancellation. Preview and generated-output memory is released when you clear the tool or leave the page.
How it works
The browser walks validated longitude and latitude positions across nested geometry collections, derives west, south, east and north, then writes those four values as bbox.
Practical example
Calculate an extent of -0.12, 51.5, -0.09, 51.53 for a local route collection and download a clean copy whose feature order and properties remain intact.
Validation
The calculation is deterministic and explains validation errors instead of silently changing invalid input.
Privacy boundary
Input and output remain in this tab. Copy and download happen through browser APIs without a server upload.
Result passport
Every run reports its tool mode, timestamp and input/output size so transformed data can be audited.