> ## Documentation Index
> Fetch the complete documentation index at: https://upstash-redis-1-18.mintlify.site/llms.txt
> Use this file 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>