Published March 9, 2026

How to Build Interview Coordination Across ATS and Calendar Platforms with ATS and Calendar APIs

March 4, 2026

Recruiting platforms often provide interview coordination tools that help hiring teams schedule, manage, and track candidate interviews. These tools allow recruiters to coordinate availability across interviewers, schedule meetings with candidates, and automatically update hiring systems.

Many SaaS products build these capabilities directly into their platforms. Instead of manually coordinating interviews across email, calendars, and ATS systems, recruiters can manage the entire workflow in one place.

The challenge is that interview data and scheduling systems live in different tools. Applicant tracking systems (ATS) such as Greenhouse or Lever store candidate and application data, while calendar systems like Outlook or Google Calendar manage availability and meeting scheduling.

Unified simplifies this process by providing normalized APIs across ATS and calendar platforms. Developers can retrieve candidate and application data from ATS systems and create interview events in calendar platforms using a consistent API.

Why SaaS Products Build Interview Coordination Features

Interview coordination is a common feature in many recruiting products.

Examples include:

Recruiting workflow platforms
Candidate scheduling tools
Hiring coordination platforms
Interview management software
AI recruiting assistants

These products help their customers manage interview workflows more efficiently.

Typical capabilities include:

Recruiter-scheduled interviews where recruiters choose available time slots
Candidate self-scheduling links that allow candidates to select interview times
Panel interview coordination with multiple interviewers
Automatic rescheduling and cancellations
Interview feedback collection workflows

By integrating with customer ATS and calendar systems, SaaS products can automate these workflows without requiring recruiters to manage them manually.

Unified Categories Used for Interview Coordination

Interview coordination combines data from two Unified API categories.

Category	Description	Key Objects
ATS	Candidate and application workflow data from platforms like Greenhouse or Lever	candidate, application, interview
Calendar & Meetings	Calendar events used to schedule interviews	calendar_event

Using normalized APIs across these categories allows SaaS platforms to coordinate interview scheduling without building separate integrations for each ATS or calendar provider.

Unified ATS Objects and Key Fields

Interview scheduling relies on several ATS objects.

Candidate

The candidate object represents the person being interviewed.

Important fields include:

Field	Purpose
id	Unique identifier for the candidate
first_name / last_name	Candidate name
emails	Used to send calendar invitations
telephones	Candidate contact information
created_at / updated_at	Record timestamps

These fields allow scheduling systems to identify the candidate and send interview notifications.

Application

The application object connects a candidate to a specific job.

Important fields include:

Field	Purpose
id	Unique identifier for the application
candidate_id	Candidate associated with the application
job_id	Job being applied for
status	Current stage in the hiring pipeline
original_status	Provider-specific stage label
applied_at	Application timestamp

Application stages often determine when interviews should be scheduled.

For example, interviews may be triggered when a candidate enters stages such as SCREENING, INTERVIEW, or FINAL_INTERVIEW.

Interview

The interview object stores interview scheduling information.

Important fields include:

Field	Purpose
id	Unique interview identifier
candidate_id	Candidate being interviewed
application_id	Application associated with the interview
job_id	Job associated with the interview
user_ids	Interviewers participating in the interview
status	Interview state (SCHEDULED, COMPLETE, CANCELED, etc.)
start_at	Interview start time
end_at	Interview end time
location	Meeting location or virtual meeting link
external_event_xref	ID of the associated calendar event
created_at / updated_at	Interview timestamps

These fields allow interview coordination tools to track interview schedules and participants.

Connecting Customer ATS and Calendars

Customers authorize their ATS and calendar platforms using Unified Connect.

Typical process:

Your application launches the Unified Connect authorization flow.
The user selects integrations such as Greenhouse, Outlook, or Google Calendar.
The user authorizes access to their accounts.
Unified redirects back with a connection_id.

Your application stores the mapping:

user_id → connection_id

All subsequent API requests reference this identifier.

Retrieving Candidate and Application Data

Interview coordination begins by retrieving candidate and application data from the ATS.

Example endpoints include:

GET /ats/{connection_id}/candidate
GET /ats/{connection_id}/application
GET /ats/{connection_id}/interview
GET /ats/{connection_id}/job

These endpoints allow the application to:

retrieve candidate contact details
identify the job associated with the interview
determine the application stage
view existing interviews

This data provides the context needed for scheduling.

Scheduling Interviews in Calendars

Once interview details are determined, the system schedules a meeting in the interviewer calendars.

Unified supports creating calendar events using:

POST /calendar/{connection_id}/event

Important writable fields include:

Field	Purpose
title	Descriptive subject for the interview
start_at	Interview start time
end_at	Interview end time
attendees	Candidate and interviewers
conference	Video meeting details
location	Physical meeting location
description	Interview agenda or preparation notes

Example event title:

Frontend Engineer Interview – Round 2

The attendees field ensures interviewers and candidates receive invitations.

The conference field allows adding Zoom, Google Meet, or Teams meeting links.

Creating and Updating ATS Interview Records

Unified also allows creating or updating interview records in the ATS.

Create an interview:

POST /ats/{connection_id}/interview

Update an interview:

PUT /ats/{connection_id}/interview/{id}

Writable fields include:

candidate_id
application_id
user_ids
status
start_at
end_at
location

These endpoints ensure the ATS remains synchronized with scheduled interviews.

Handling Rescheduling and Cancellations

Interview coordination tools must react to scheduling changes.

Unified provides webhook events that notify applications when calendar events change.

Important events include:

event.created
event.updated
event.deleted

These events allow scheduling systems to:

update interview times
notify participants
cancel interviews when necessary

Supported Platforms

Unified supports a wide range of hiring and scheduling integrations.

ATS Platforms (73 integrations)

Examples include:

Greenhouse
Lever
Ashby
SmartRecruiters
iCIMS
Workday
Jobvite
BambooHR
Workable

Calendar Platforms (27 integrations)

Examples include:

Google Calendar
Microsoft Outlook
Zoom Calendar
Calendly
Apple iCloud
Webex

This allows recruiting platforms to support many customer environments without building separate integrations.

Why Product Teams Choose Unified

Building interview coordination features typically requires integrating with multiple ATS platforms and calendar systems.

Unified simplifies this by providing:

normalized ATS objects for candidates, applications, and interviews
unified calendar APIs for scheduling events
consistent authentication through Unified Connect
webhook events for real-time updates

Instead of maintaining dozens of integrations, product teams can focus on building recruiting workflows that help hiring teams schedule and manage interviews efficiently.

Start building interview coordination across Greenhouse, Outlook, Google Calendar, and dozens of other platforms today.

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