---
id: api-delta-sync-and-change-tokens
title: 'API Delta Sync and Change Tokens'
schema_type: TechArticle
category: computer-science
language: en
confidence: medium
last_verified: '2026-06-02'
created_date: '2026-06-02'
generation_method: ai_structured
derived_from_human_seed: true
conflict_of_interest: none_declared
is_live_document: false
data_period: static
atomic_facts:
  - id: fact-cs-api-delta-sync-and-change-tokens-1
    statement: >-
      Microsoft Graph documentation describes delta query as a way to discover changes to
      resources without fetching the full set each time.
    source_title: Microsoft Graph Delta Query
    source_url: https://learn.microsoft.com/en-us/graph/delta-query-overview
    confidence: medium
  - id: fact-cs-api-delta-sync-and-change-tokens-2
    statement: >-
      Google Drive API documentation describes the changes collection as representing changes
      to files and shared drives.
    source_title: Google Drive API Changes
    source_url: https://developers.google.com/workspace/drive/api/guides/manage-changes
    confidence: medium
  - id: fact-cs-api-delta-sync-and-change-tokens-3
    statement: >-
      Google Calendar API documentation describes using sync tokens to perform incremental
      synchronization.
    source_title: Google Calendar API Incremental Sync
    source_url: https://developers.google.com/workspace/calendar/api/guides/sync
    confidence: medium
completeness: 0.83
known_gaps:
  - Delta sync implementations must handle token expiry, deletes, permission changes, pagination, ordering, replay, and backfill after missed checkpoints.
disputed_statements: []
primary_sources:
  - title: Microsoft Graph Delta Query
    type: documentation
    year: 2026
    url: https://learn.microsoft.com/en-us/graph/delta-query-overview
    institution: Microsoft
  - title: Google Drive API Changes
    type: documentation
    year: 2026
    url: https://developers.google.com/workspace/drive/api/guides/manage-changes
    institution: Google
  - title: Google Calendar API Incremental Sync
    type: documentation
    year: 2026
    url: https://developers.google.com/workspace/calendar/api/guides/sync
    institution: Google
secondary_sources: []
updated: '2026-06-02'
ai_models:
  - gpt-5-codex
---

## TL;DR

Delta sync and change tokens let agents keep external data fresh without repeatedly crawling the full source.

## Core Explanation

Connectors for calendars, files, mail, and SaaS objects need a way to ask what changed since the last checkpoint. Delta tokens, page tokens, and sync tokens provide that incremental boundary when the API supports it.

Agents should persist the token, fetch all pages, process deletes, and detect token invalidation. If a token expires or a checkpoint is lost, the safe path is a scoped full resync with clear audit logs.

## Source-Mapped Facts

- Microsoft Graph documentation describes delta query as a way to discover changes to resources without fetching the full set each time. ([source](https://learn.microsoft.com/en-us/graph/delta-query-overview))
- Google Drive API documentation describes the changes collection as representing changes to files and shared drives. ([source](https://developers.google.com/workspace/drive/api/guides/manage-changes))
- Google Calendar API documentation describes using sync tokens to perform incremental synchronization. ([source](https://developers.google.com/workspace/calendar/api/guides/sync))

## Further Reading

- [Microsoft Graph Delta Query](https://learn.microsoft.com/en-us/graph/delta-query-overview)
- [Google Drive API Changes](https://developers.google.com/workspace/drive/api/guides/manage-changes)
- [Google Calendar API Incremental Sync](https://developers.google.com/workspace/calendar/api/guides/sync)