Fb Compact Serialize

:::info[Note] This is a point-in-time snapshot of the API documentation from January 2026. Going forward, we will not be maintaining a public copy of these references, and recommend users to refer to the built-in signature helpers available in the Hack LSP instead for complete and up-to-date information. :::

Serialize data into a compact format that can be unserialized by fb_compact_unserialize()

function fb_compact_serialize(
  mixed $thing,
  int $options = 0,
): mixed;

In general produces smaller output compared to fb_serialize(). Largest savings are on arrays with sequential (or almost sequential) indexes, i.e. simple arrays like array($a, $b, $c). NOTE: unlike serialize(), does not preserve internal references, i.e. array(&$a, &$a) will become array($a, $a).

Parameters

• mixed $thing - What to serialize. Note that objects are not supported.
• int $options = 0

Returns

• mixed - - Serialized data.