> ## Documentation Index
> Fetch the complete documentation index at: https://upstash-dx-3081-agentkit-tanstack-ai-backends.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>


## Related topics

- [PFADD](/redis/commands/hyperloglog/pfadd.md)
- [PFMERGE](/redis/commands/hyperloglog/pfmerge.md)
- [REST API](/redis/features/restapi.md)
- [SUNIONCARD](/redis/commands/set/sunioncard.md)
- [PFCOUNT](/redis/commands/hyperloglog/pfcount.md)