Free and open-source calendar for Windows with no account, no sync, and nothing phoning home. Month, week, day and agenda views, repeating appointments, color categories, iCalendar import and export, and optional AES-256 encryption at rest. Your appointments live in a single .kcal file on your own machine - an ordinary SQLite database until you put a password on it. Install or run portable. Single Windows EXE, ~3 MB, no runtime install required.

Internals, formats, storage details, and limits live on the technical page.

Features

• Four views - month, week, day and agenda - with one shared previous / next / today control; Month zooms from one to six visible weeks and draws multi-day appointments as continuous runs
• Appointments edited in a slide-out sidebar panel, not a dialog: title, start and end, all-day, location, description and attendees
• Repeating appointments - daily, weekly on the days you tick, monthly or yearly, every N of those, ending never, after a count, or on a date - with per-date exceptions; editing or deleting one date asks whether you mean just that date or the whole series
• Drag to move appointments across times and days; overlapping appointments sit side by side instead of hiding one behind the other
• Color categories you define, painting every view; a 5-day work week toggle and a grid density control down to quarter hours
• Import and export in the formats people actually hand you: iCalendar (.ics, RFC 5545) both ways, CSV in Outlook's column format both ways, saved email invites (.eml) in, and a themed month-by-month web page out with a print stylesheet
• Optional encryption: the lock button puts a password on a Killendar and it is encrypted at rest with SQLCipher (AES-256, per-page HMAC-SHA512); opt-in, so no password means a plain readable SQLite file
• As many Killendars as you like - work, on-call, family - each its own .kcal file with its own password or none; keep them in the default profile folder, another folder you choose, or beside the portable executable
• Thirteen themes - Dark, Light, Black, 98SE, Blood, Greed, Cyanotic, Ectoplasm, Decay, Mourning, Sepulchre, Delirium and Malaise - four of them (Dark, Light, Black and 98SE) take six accent hues each, so 33 looks in all; twelve languages switchable without a restart (contribute via TRANSLATING.md)
• Keyboard driven with single-key shortcuts; full keyboard shortcut overlay on F1 with list and visual keyboard views
• Runs portable, or self-installs per-user (no UAC) or machine-wide (/silent for scripted deployment); uninstalls cleanly and never deletes your appointments
• Verified code signing shown in the About card, checked with WinVerifyTrust rather than just read off the file
• Local-only: no account, no telemetry, no phone-home

Screenshots

Month view - A full August of appointments, with all-day runs banded across the top of each day, on the Delirium theme.	Week view - A five-day work week, overlapping appointments packed into lanes, on the Decay theme.
Day view - One wall-to-wall day in the hour grid beside the day list, on the 98SE theme.	Shortcuts map - The F1 overlay's keyboard view, every bound key lit and labeled, on the Black theme.

Requirements

• Windows 10 or 11 (x64)
• No runtime install. Everything needed is inside the EXE (targets .NET Framework 4.8, which ships with every supported Windows release).

Download

WinGet:

winget install killendar

• Prebuilt binary: https://github.com/SteveTheKiller/Killendar/releases/latest/download/Killendar.exe
• Source (GPL3 corresponding source for this release): https://github.com/SteveTheKiller/Killendar/releases/download/v1.1.0/Killendar-1.1.0-src.zip

Build from source

git clone https://github.com/SteveTheKiller/Killendar.git
cd Killendar
dotnet build Killendar.csproj -c Release

Requires the .NET Framework 4.8 developer pack and Visual Studio 2022 (or the Build Tools).

brand/ holds the working artwork and is not tracked. Everything the app consumes is generated out of it into Resources/, which is tracked, so a fresh clone builds without it.

Changelog

See CHANGELOG.md.

License

GPLv3. See LICENSE. If you fork, modify, or redistribute Killendar, your version must also be released under GPLv3 with source available. No exceptions for commercial rebrands.