# Holder API

## Holder API

- [Overview](https://docs.holder.xyz/holder-api/readme.md)
- [Authentication](https://docs.holder.xyz/holder-api/authentication.md)
- [Security](https://docs.holder.xyz/holder-api/security.md)
- [Adding a Contact](https://docs.holder.xyz/holder-api/contacts/adding-a-contact.md)
- [Get Contacts](https://docs.holder.xyz/holder-api/contacts/get-contacts.md)
- [Contact Fields](https://docs.holder.xyz/holder-api/contacts/contact-fields.md)
- [Merging Contacts](https://docs.holder.xyz/holder-api/contacts/merging-contacts.md)
- [Tags](https://docs.holder.xyz/holder-api/contacts/tags.md): Add ability to get, create, and apply tags from contacts
- [Traits](https://docs.holder.xyz/holder-api/nft-data/traits.md)