dCal — A place to write down your days

Preview — Mac

Real screenshots from dCal on macOS with demo data loaded. Colored bars flow across week boundaries; each day cell shows its own rich-text notes inline. Click any day to open the formatted long-form editor.

dCal Mac 4-week grid with period bars and in-cell day notes — 4-week grid · in-cell notes · period events

Day editor with rich-text markup and live preview pane — Day editor — markup & live preview

Full-text search across notes and period event titles — Full-text search (⌘F)

Date jump popover with year scroller and 12-month grid — Jump to any date (⌘J)

Preview — iPhone

The same .cal file opens on iPhone. If you sync via iCloud Drive or Dropbox, notes typed on Mac show up instantly on iPhone with the same formatting tags.

dCal 4-week grid with colored period bars — 4-week grid & period events

Day editor modal — markup with rendered preview below — Long-form notes — markup + preview

Period event editor — color, line style, arrows — Period event editor

Search sheet — full-text across notes and event titles — Full-text search

Settings — week start, weeks shown, appearance — Settings & appearance

Why local-first?

Cloud-based calendars	dCal (local-first)
The app auto-syncs to the vendor's servers	The app makes no network calls at all
Your data may be used for AI training or ad targeting	Nothing leaves the app's process
Account compromise = full schedule leaked	No account exists in the first place
Subscription ends → data locked away	Plain-text files, yours forever
Sync is hardwired to the vendor	You choose: iCloud / Dropbox / nothing
Monthly view splits multi-month events	4-week continuous grid
Events are mostly just a title	Unlimited per-day notes with formatting

"The app cannot talk to the network" — provable, not a slogan

$ codesign -d --entitlements - dCal.app

  com.apple.security.app-sandbox          ← enabled
  com.apple.security.files.user-selected  ← enabled (file picker only)

  com.apple.security.network.client       ← absent
  com.apple.security.network.server       ← absent

macOS App Sandbox grants dCal zero network entitlements, so the OS itself refuses any outbound connection from the app. If you choose to sync via iCloud Drive or Dropbox, your .cal file does pass through those services — but that's a sync method you picked, not something dCal does on its own.

Features

4-week grid view

Switch between 3 and 6 weeks. Multi-day events render as continuous colored lines that don't break at month boundaries — something Apple Calendar's monthly view can't do.

Long-form notes per day

Every day cell holds unlimited text — meeting minutes, work logs, family notes. Markdown-style formatting (bold, italic, color) plus full-text search across all your notes.

Japanese holidays built-in

Including substitute holidays and citizens' holidays. Computed from the official statute, valid 1980 to 2099, no online lookup required.

Jump to any date (⌘J)

Horizontal year scroller plus a 12-month grid in a single popover. Two clicks to reach 2003 or 2099.

Fast full-text search (⌘F)

Search every day note and event title with match highlighting. Stays instant even on multi-thousand-entry files.

Mac + iPhone — you choose how to sync

Use iCloud Drive, Dropbox, Google Drive, OneDrive, or no sync at all. dCal never talks to those services' APIs — it just reads the file your sync client puts on disk.

Plain text, forever

No proprietary binary. Your .cal file remains human-readable. Even without dCal twenty years from now, your data stays alive.

hyCalendar file compatibility

dCal opens .cal files from the Windows freeware hyCalendar byte-for-byte unchanged. If you've used hyCalendar for years and want to keep going on macOS, this is your path.

Who it's for

⚖️ Lawyers, accountants, tax advisors

Client and case names should never be on a cloud you don't own

🩺 Doctors, therapists, dentists

Patient identifiers, appointment data — all sensitive

🏢 Executives

M&A, hiring, board meetings — schedules you can't risk leaking

✍️ Writers and freelancers

Daily logs and source meetings worth keeping long-form

👨‍👩‍👧 Family schedule keepers

Want four weeks at a glance, without signing the family up for an account

📜 hyCalendar veterans

Migrating to Apple but keeping decades of .cal data

Pricing

$19.99 one-time

Universal Purchase unlocks Mac and iOS

✔ No subscription
✔ No account required
✔ Family Sharing supported
✔ Free updates
✔ Privacy policy explicitly states "the app sends no data"

FAQ

Q. Where is my data stored?

Wherever you choose. You can keep everything on a local disk, or place the file in iCloud Drive / Dropbox to share between devices. The point is: you pick the location. dCal never auto-sends your file anywhere.

Q. So there's no built-in cloud sync?

Correct. dCal does not talk to any cloud service of its own. If you want multi-device sync, place the .cal file in iCloud Drive, Dropbox, Google Drive, OneDrive, etc., and dCal reads the synced local copy. Fully offline operation is also supported.

Q. If I sync via iCloud Drive or Dropbox, isn't my data still in the cloud?

Yes, that's true. If you place the file on iCloud Drive or Dropbox, the data lives on those clouds. But dCal itself does not talk to any of them — you decide which cloud to use, or none at all. Cloud-based calendars like Google Calendar lock you into the vendor's servers; that's the fundamental difference.

Q. Can I open Windows hyCalendar files?

Yes, byte-for-byte compatible. Real-world files (3 MB+, 7,000 day entries, 1,700 period events) load without issue.

Q. Will my data be used for AI training?

Not via dCal — the app cannot transmit anything. If you choose to sync via iCloud Drive or Dropbox, any downstream data handling falls under those services' privacy policies. To eliminate all external transmission, keep your files local-only.

Q. Do you offer business / volume licensing?

Planned for 2027. Please contact us.