> ## Documentation Index
> Fetch the complete documentation index at: https://docs.topsort.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Linking Users
export const LastUpdated = ({date, lang = "en"}) => {
const translations = {
en: "Last updated:",
es: "Última actualización:",
pt: "Última atualização:",
fr: "Dernière mise à jour:",
de: "Zuletzt aktualisiert:"
};
const label = translations[lang] || translations.en;
return <>
;
};
Accurate attribution requires connecting user activity across logged-out and logged-in states. Topsort provides API tools to solve this issue, enabling you to link two opaque user IDs.
### How It Works
Users often interact with ads while logged out (e.g., `user_id` = 123) and later, they log in, gaining a distinct user ID (e.g., `user_id` = 456). Without linking these IDs, activities from the logged-out session are disconnected from post-login actions, leading to inaccurate attribution.
Our [Link Users API](http://api.docs.topsort.com/api-reference/events/\[beta]-report-link-users#beta-report-link-users) enables you to inform Topsort that two opaque user IDs belong to the same person. Improving attribution accuracy. Required fields to use our API:
Field | Type | Required | Description |
`from` | **STRING** | yes | The original (e.g., logged-out) opaque user ID. (1-64 chars) |
`to` | **STRING** | yes | The target (e.g., logged-in) opaque user ID. (1-64 chars) |
`from` and `to` IDs must not be identical.
***