> ## Documentation Index
> Fetch the complete documentation index at: https://docs.replyke.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Collection

> A named folder in a user's personal save library for organizing entities

## Overview

A `Collection` is a user-owned, hierarchical folder used to save and organize entities. Every user has a single root collection created automatically on first access. Users can create any number of sub-collections nested under the root or under other sub-collections.

Collections are private — each collection belongs to one user and is not visible to others.

## Fields

<ResponseField name="id" type="string">
  Unique identifier for the collection (UUID).
</ResponseField>

<ResponseField name="projectId" type="string">
  The project this collection belongs to.
</ResponseField>

<ResponseField name="userId" type="string">
  The user who owns this collection.
</ResponseField>

<ResponseField name="parentId" type="string | null">
  The ID of the parent collection. `null` for the root collection.
</ResponseField>

<ResponseField name="name" type="string">
  Display name of the collection. The root collection is always named `"root"`.
</ResponseField>

<ResponseField name="entityCount" type="number">
  Number of entities directly saved in this collection (not counting sub-collections).
</ResponseField>

<ResponseField name="createdAt" type="string (ISO 8601)">
  Timestamp when the collection was created.
</ResponseField>

<ResponseField name="updatedAt" type="string (ISO 8601)">
  Timestamp when the collection was last modified.
</ResponseField>

## Notes

* The root collection is created lazily on the first call to `GET /:projectId/api/v7/collections/root`.
* The root collection cannot be renamed or deleted.
* Sub-collections can be nested to any depth.
* Entities are linked to collections via a junction table — the same entity can be saved in multiple collections.