The set of valid transactions each node has received but not yet seen in a block. It is not a single global queue — every node keeps its own — but they broadly agree, and it is the closest thing Bitcoin has to a waiting room.

Why do fees rise when it fills?

Because block space is fixed and demand is not. Miners take the highest-paying transactions first, so when more transactions are waiting than fit, users bid against each other and the clearing rate rises.

Yes. It comes from Blockstream's public mempool endpoint, key-free. Nothing is invented or simulated, and if the source cannot be reached the saver reports that instead of drawing something plausible.

Does it cost anything or need an account?

No. Every screensaver here is free, runs in the browser and needs no sign-up. This one uses a public API that requires no key.

The Fee Auction Screensaver

The Fee Auction screensaver draws Bitcoin's mempool — every transaction broadcast but not yet confirmed — as a histogram of fee rates. Each bar is a fee band and the transaction weight waiting at that price. It runs in the browser with nothing to install; press ESC to exit.

How the The Fee Auction screensaver works

The saver reads Blockstream's public mempool endpoint, key-free.

No account and no key: the request goes straight from your browser, or from this site's own refreshed copy of the feed where the source does not permit browser access.

Values are drawn on a canvas that resizes with the window, so it works on a laptop or a wall display.

If the source is unreachable the saver says so on screen rather than showing stale numbers as though they were current.

A worked example

Three figures across the top: transactions waiting, how many blocks it would take to clear them, and the total fees pending. Beneath is the histogram, fee rate increasing to the right. Since a block clears roughly one million virtual bytes, everything stacked above your fee rate is what has to be confirmed before you are.

Settings & tips

Accent and Background recolour the display without changing the data.
Add it to a Multi-view grid to watch it alongside other live savers.
Press ESC at any time to leave fullscreen.

Frequently asked questions

What is the mempool?: The set of valid transactions each node has received but not yet seen in a block. It is not a single global queue — every node keeps its own — but they broadly agree, and it is the closest thing Bitcoin has to a waiting room.
Why do fees rise when it fills?: Because block space is fixed and demand is not. Miners take the highest-paying transactions first, so when more transactions are waiting than fit, users bid against each other and the clearing rate rises.
Is this real data?: Yes. It comes from Blockstream's public mempool endpoint, key-free. Nothing is invented or simulated, and if the source cannot be reached the saver reports that instead of drawing something plausible.
Does it cost anything or need an account?: No. Every screensaver here is free, runs in the browser and needs no sign-up. This one uses a public API that requires no key.

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