Cloud Optimized HTTP Request

This satellite photo of Venice is one single 316 MB file (a Cloud-Optimized GeoTIFF) on a public server. Pan and zoom — your browser fetches only the pieces it needs, and they light up in the stack on the right. Every number is a real request.

The photo

drag to pan · scroll to zoom — the frame is the edge of the photo

Contacting the server…
—
Waking up…

Inside the file — the same photo, stored 5 times

each layer covers the same area, just sharper (and heavier) as you go down — the outlined patch is what your map shows right now · tiles blink while downloading, then stay lit

0 KB
of the 316.6 MB file · 0%
0 requests
the whole file, byte by byte (to scale) — dark = bytes your browser fetched
built with Fused Render  ·  made by Max Lenormand

The trick has a name: this file is a Cloud-Optimized GeoTIFF (COG). It keeps a table of contents at the front and stores the photo as ready-made zoom levels cut into tiles — so any viewer on the internet can grab just the bytes it needs, with plain HTTP Range requests (the same header your video player uses to skip ahead).

Anatomy of one request — hover a row below to inspect it

–

Every HTTP request (newest first)

Details

FileTCI.tif · Sentinel-2 · 12 Aug 2025
Full image—
Zoom levels inside—
Exact bytes fetched0
— beyond the tiles you needed0
Median request time—
Block size (restarts the demo)
Reads are rounded to 64 KB blocks — the client's granularity knob: bigger blocks mean fewer requests but more spill into neighbouring tiles; smaller means tighter but chattier. Try a range request yourself: