https://github.com/icaldav/icaldav

A Kotlin CalDAV client with offline sync and conflict resolution. Sync calendars with iCloud, Nextcloud, and other CalDAV servers.
https://github.com/icaldav/icaldav

android baikal caldav calendar calendar-sync google-calendar icalendar icloud jvm kotlin library nextcloud radicale rfc5545 sync webdav

Last synced: 5 months ago
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A Kotlin CalDAV client with offline sync and conflict resolution. Sync calendars with iCloud, Nextcloud, and other CalDAV servers.

Host: GitHub
URL: https://github.com/icaldav/icaldav
Owner: iCalDAV
License: apache-2.0
Created: 2026-01-09T21:46:48.000Z (5 months ago)
Default Branch: main
Last Pushed: 2026-01-25T23:31:24.000Z (5 months ago)
Last Synced: 2026-01-26T14:49:53.642Z (5 months ago)
Topics: android, baikal, caldav, calendar, calendar-sync, google-calendar, icalendar, icloud, jvm, kotlin, library, nextcloud, radicale, rfc5545, sync, webdav
Language: Kotlin
Homepage: https://icaldav.github.io
Size: 831 KB
Stars: 3
Watchers: 1
Forks: 0
Open Issues: 0
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
- Code of conduct: CODE_OF_CONDUCT.md
- Security: SECURITY.md
- Notice: NOTICE

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README

          # iCalDAV

[![Maven Central](https://img.shields.io/maven-central/v/org.onekash/icaldav-client)](https://central.sonatype.com/namespace/org.onekash)

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[![Kotlin](https://img.shields.io/badge/kotlin-1.9+-purple.svg)](https://kotlinlang.org)

A Kotlin CalDAV client with offline sync and conflict resolution. Sync calendars with iCloud, Nextcloud, and other CalDAV servers.

## RFC Compliance

| RFC | Title | Status |

|-----|-------|--------|

| [RFC 5545](https://datatracker.ietf.org/doc/html/rfc5545) | iCalendar Core (VEVENT, VTODO, VJOURNAL, RRULE) | ✅ Full |

| [RFC 5546](https://datatracker.ietf.org/doc/html/rfc5546) | iTIP (iCalendar Transport-Independent Interoperability) | ✅ Full |

| [RFC 4918](https://datatracker.ietf.org/doc/html/rfc4918) | WebDAV (PROPFIND, REPORT, PUT, DELETE) | ✅ Full |

| [RFC 4791](https://datatracker.ietf.org/doc/html/rfc4791) | CalDAV (calendar-query, calendar-multiget) | ✅ Full |

| [RFC 6578](https://datatracker.ietf.org/doc/html/rfc6578) | WebDAV Sync (sync-collection, sync-token) | ✅ Full |

| [RFC 3744](https://datatracker.ietf.org/doc/html/rfc3744) | WebDAV ACL (access control, privileges) | ✅ Full |

| [RFC 6638](https://datatracker.ietf.org/doc/html/rfc6638) | CalDAV Scheduling (iTIP delivery, free-busy) | ✅ Full |

| [RFC 7986](https://datatracker.ietf.org/doc/html/rfc7986) | New iCalendar Properties (COLOR, IMAGE, CONFERENCE) | ✅ Full |

| [RFC 9073](https://datatracker.ietf.org/doc/html/rfc9073) | Event Publishing Extensions (VLOCATION, PARTICIPANT) | ✅ Full |

| [RFC 9074](https://datatracker.ietf.org/doc/html/rfc9074) | VALARM Extensions (ACKNOWLEDGED, UID, PROXIMITY) | ✅ Full |

| [RFC 9253](https://datatracker.ietf.org/doc/html/rfc9253) | iCalendar Relationships (LINK, enhanced RELATED-TO) | ✅ Full |

| [RFC 6047](https://datatracker.ietf.org/doc/html/rfc6047) | iMIP (email-based scheduling) | ⬜ Out of scope |

## Features

### iCalendar (RFC 5545)

- Complete VEVENT, VTODO, and VJOURNAL parsing and generation

- Recurring events (RRULE, RDATE, EXDATE, RECURRENCE-ID)

- Access classification (CLASS property: PUBLIC, PRIVATE, CONFIDENTIAL)

- All-day and multi-day event support

- Timezone handling with VTIMEZONE and timezone distribution service

- Alarms (VALARM) with DISPLAY, EMAIL, and AUDIO actions

### CalDAV Protocol

- CalDAV client with automatic server discovery

- WebDAV ACL support (RFC 3744) - read and modify access control

- CalDAV Scheduling (RFC 6638) with iTIP message building

- Sync engine with offline support and conflict resolution

- Provider quirks handling (iCloud, Nextcloud, Radicale, Baikal)

## Installation

```kotlin

// build.gradle.kts

dependencies {

    implementation("org.onekash:icaldav-client:2.6.2")

    // Optional: Sync engine with offline support

    implementation("org.onekash:icaldav-sync:2.6.2")

    // Optional: Android CalendarContract mapper (API 21+)

    implementation("org.onekash:icaldav-android:2.6.2")

}

```

**Requirements:** JVM 17+, Kotlin 1.9+. Android module requires API 21+.

## Quick Start

```kotlin

import org.onekash.icaldav.client.CalDavClient

import org.onekash.icaldav.model.ICalEvent

import org.onekash.icaldav.model.ICalDateTime

import org.onekash.icaldav.model.DavResult

import java.time.Instant

import java.time.temporal.ChronoUnit

import java.util.UUID

// Create client

val client = CalDavClient.forProvider(

    serverUrl = "https://caldav.example.com",

    username = "user@example.com",

    password = "password"

)

// Discover calendars

val discovery = client.discoverAccount("https://caldav.example.com")

if (discovery is DavResult.Success) {

    val calendarUrl = discovery.value.calendars.first().href

    // Create event

    val event = ICalEvent(

        uid = UUID.randomUUID().toString(),

        summary = "Team Meeting",

        dtStart = ICalDateTime.fromInstant(Instant.now()),

        dtEnd = ICalDateTime.fromInstant(Instant.now().plus(1, ChronoUnit.HOURS))

    )

    val createResult = client.createEvent(calendarUrl, event)

    if (createResult is DavResult.Success) {

        val (href, etag) = createResult.value

        // Update event

        val updated = event.copy(summary = "Team Meeting (Updated)")

        client.updateEvent(href, updated, etag)

        // Delete event

        client.deleteEvent(href, etag)

    }

    // Fetch events in date range

    val start = Instant.now()

    val end = Instant.now().plus(30, ChronoUnit.DAYS)

    val events = client.fetchEvents(calendarUrl, start, end)

}

```

### Error Handling

All operations return `DavResult`:

```kotlin

when (val result = client.fetchEvents(calendarUrl, start, end)) {

    is DavResult.Success -> handleEvents(result.value)

    is DavResult.HttpError -> println("HTTP ${result.code}: ${result.message}")

    is DavResult.NetworkError -> println("Network: ${result.exception.message}")

    is DavResult.ParseError -> println("Parse: ${result.message}")

}

```

## Modules

| Module | Purpose |

|--------|---------|

| `icaldav-core` | Parse and generate iCalendar (RFC 5545) |

| `icaldav-client` | CalDAV/WebDAV client with discovery and CRUD |

| `icaldav-sync` | Sync engine with offline support and conflict resolution |

| `icaldav-android` | Android CalendarContract mapper (API 21+) |

## Tested Providers

| Provider | Notes |

|----------|-------|

| **iCloud** | CDATA responses, namespace quirks, regional redirects, app-specific passwords |

| **Nextcloud** | Standard CalDAV |

| **Radicale** | Direct URL access (skip discovery) |

| **Baikal** | sabre/dav based, standard CalDAV |

Other CalDAV servers following RFC 4791 should work. [Open an issue](https://github.com/iCalDAV/iCalDAV/issues) if you encounter problems.

## Links

- [Maven Central](https://central.sonatype.com/namespace/org.onekash)

- [GitHub](https://github.com/iCalDAV/iCalDAV)

- [Contributing](CONTRIBUTING.md)

## License

Apache License 2.0

ecosyste.ms

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