# Legacy Documentation

- [Custom user ID (V3)](/developer/sdk/web/legacy-documentation/customid-v3.md)
- [Attributes (V3)](/developer/sdk/web/legacy-documentation/custom-attributes-v3.md)
- [Events (V3)](/developer/sdk/web/legacy-documentation/custom-events-v3.md)
- [Choosing the HTTP/Multidomain mode](/developer/sdk/web/legacy-documentation/unsecure-mode.md)