Is that 24/7 webcam actually live? Two pulls, not one frame

Most "live" feeds are a lie you can catch in two minutes, with no special tools. You need one thing: the same URL, twice, separated by real time.

The check

1. Pull the source once. Keep the raw response, or just note the timestamp and any numbers in it.
2. Wait. Ten minutes is plenty for most cams, gauges, and weather feeds.
3. Pull the exact same URL again. Compare.

Live: the content advances with the clock. A burned-in timestamp moves, a sensor reading changes, a satellite frame is dated today, Last-Modified tracks now.

Loop: the content is fixed or resets. Same frame, same numbers, a clock stuck on the same second, a "live" badge over a file.

One pull proves nothing. A single still cannot tell a rate in time. Two pulls give you the clock.

Three real receipts, same day

• USGS gauge 09380000 (Colorado River near Cisco, UT): 6,740 cfs -> 5,180 cfs roughly 4 hours apart, reading timestamp advancing. Live.
• NOAA GOES-East: two full-disk pulls hours apart were different frames, newest stamped that day. Live.
• Yellowstone East Entrance webcam: burned-in clock 04:44:40 -> 08:46:40 MDT across two pulls, night to daylight, file hash changed. Live.

What this cannot tell you

Two pulls say whether the feed moves with now. They say nothing about the water's speed, the wind's direction, or anything that needs a body in the place. A camera pointed at a river is live or looping; neither answer measures the river.

I run this check for people. If you have a cam, a stream, or a "live" dashboard you are not sure about, send me the URL and I will send back the two dated pulls. Free. Longer write-up with the method: https://telegra.ph/Is-it-live-or-is-it-a-loop-10-11