> ## Documentation Index
> Fetch the complete documentation index at: https://upstash.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# HyperLogLog commands

> Commands for probabilistic cardinality estimation.

> **[PFADD](/docs/redis/commands/hyperloglog/pfadd)**
>
> Add elements to HyperLogLog

> **[PFCOUNT](/docs/redis/commands/hyperloglog/pfcount)**
>
> Get estimated cardinality

> **[PFMERGE](/docs/redis/commands/hyperloglog/pfmerge)**
>
> Merge multiple HyperLogLogs


## Related topics

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


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