Introduction

# Countly API Documentation Documentation ## API Reference - [Introduction](https://api.count.ly/reference/rest-api-reference.md) - [/i](https://api.count.ly/reference/i.md): Writing sessions, metrics and events - [/api-key](https://api.count.ly/reference/api-key.md): Retrieve user's API_KEY - [/o/users/all](https://api.count.ly/reference/ousersall.md): Retrieve information about all users - [/o/users/me](https://api.count.ly/reference/ousersmeapi_keyapi_key.md): Retrieve information about user - [/o/apps/all](https://api.count.ly/reference/oappsall.md): Retrieve information about all apps - [/o/apps/mine](https://api.count.ly/reference/oappsmine.md): Retrieve information about user's apps - [/o/apps/details](https://api.count.ly/reference/oappsdetails.md): Retrieve detailed information about app users (available from v16.12) - [/o?method=locations](https://api.count.ly/reference/omethodlocations.md): Retrieve locations of the app - [/o?method=sessions](https://api.count.ly/reference/omethodsessions.md): Retrieve session information of the app - [/o?method=users](https://api.count.ly/reference/omethodusers.md): Retrieve users of the app - [/o?method=devices](https://api.count.ly/reference/omethoddevices.md): Retrieve devices information of the app - [/o?method=device_details](https://api.count.ly/reference/omethoddevice_details.md): Retrieve device details data of the app - [/o?method=carriers](https://api.count.ly/reference/omethodcarriers.md): Retrieve carriers of the app - [/o?method=app_versions](https://api.count.ly/reference/omethodapp_versions.md): Retrieve app versions data of the app - [/o?method=cities](https://api.count.ly/reference/omethodcities.md): Retrieve city locations of the app - [/o?method=events](https://api.count.ly/reference/omethodevents.md): Retrieve events of the app - [/o?method=get_events](https://api.count.ly/reference/omethodget_events.md): Retrieve list of events of the app - [/o?method=get_period_obj](https://api.count.ly/reference/o