Broker RaidSave is an Ace3/LDB plugin that allows tracking of raid IDs across characters. It started out as a "port" based on FuBar_RaidSaveFu, with permission from jokeyrhyme, the author of the original, but eventually followed a different path.
The plugin will display the number of active (and optionally expired) saved instances for the current character on the button/block, separated into a [Group]:[Raid]:[Expired] format and will also display a list of alt characters, along with their saved instance ID's and expiration times, on the tooltip. The tooltip provides clickable functionality, allowing the player to paste instance information in an open chat box, or toggle extension of active (or even expired) instance IDs. Right-clicking the plugin, will toggle display of Blizzard's Raid Information frame.
The addon obviously has to have been used on a character before any of their information will be available.
You may configure the information shown on the button/tooltip by right clicking on the plugin and setting the appropriate options to your liking, on the addon configuration panel.
The addon should be considered beta quality, yet stable enough to warrant a release. Please report any issues you encounter, especially when it comes to proper detection of saved instances.
Bear in mind that Broker RaidSave, as all DataBroker plugins does not provide it's own display, you will need a LDB-based display addon, such as Fortress, Carousel, StatBlockCore, Titan Panel etc.