> ## Documentation index
> Fetch the complete documentation index at: https://upstash.com/docs/llms.txt
> Search it with GET https://upstash.com/docs/search?q=<query>.
> Use these to discover all available pages before exploring further.

# HyperLogLog commands

> Commands for probabilistic cardinality estimation.

<CardGroup cols={2}>
<Card title="PFADD" href="/redis/commands/hyperloglog/pfadd">Add elements to HyperLogLog</Card>
<Card title="PFCOUNT" href="/redis/commands/hyperloglog/pfcount">Get estimated cardinality</Card>
<Card title="PFMERGE" href="/redis/commands/hyperloglog/pfmerge">Merge multiple HyperLogLogs</Card>
</CardGroup>