Dayside

English · 简体中文

Before you message someone in Tokyo, look at their sky.

Dayside is a world clock for the Mac menu bar. Every place you add gets a row, and the row is painted in the real color of its sky at this moment: dark at night, bright in the daytime, a little rose at dawn and amber at dusk. You can tell at a glance who is asleep.

I made Dayside for the questions that come up every time I talk to someone in another time zone: what time it is there, whether they are awake, when we can meet without someone staying up late, and when daylight saving time changes.

What it looks like

Click the clock in the menu bar and a panel opens. At the top is a world map with the half of the Earth that the sun lights right now, and the line between day and night. Under it, each of your places has its row of sky, its local time and how far ahead or behind you it is. There is a search field that also understands natural language like "tomorrow 9:00 Tokyo".

Time can be shifted: drag the map or the time slider, and the sun, the day-and-night line and every clock move together. Double-click the map to open the Earth window: a big map with your places and their local times, and the lights of cities on the night side (only cities with a large enough population get lights). It can go full screen.

The app has no Dock icon. It lives in the menu bar.

What you can do with it

• Show one to six clocks in the menu bar, with place names, abbreviations or UTC offsets.
• Search cities offline. The search knows local names in many languages, short city names like NYC or HK, country names like UK, and time zone offsets. Sunrise and sunset use each city's own coordinates.
• Dates, times, places and time zones written in 16 languages: Dayside can find them in a whole block of text. Paste a chat message or an email. When a time can be read two ways, it shows both and lets you pick. When a time cannot be real, it says so.
• Find a meeting time that works for everyone. For a regular meeting, Dayside can rotate the bad hours, so the same people do not always stay up late. Then add it to your calendar.
• Use the other pages in the Time Tools window: Calendar, People, Time Conversion, Timers, Daylight Saving Alerts, Sun and Moon, Market Clock, Travel and Share My Time. Each page loads only when you open it.
• Use it from Shortcuts, Spotlight, the Services menu ("Convert Time with Dayside") or a global shortcut (off by default).

The time reading runs entirely on your Mac with fixed rules written in Rust. The same text always gives the same answer (no guessing). For the hour that daylight saving skips or repeats, Dayside uses the system's own time zone rules.

The 16 interface languages are English, Simplified Chinese, Traditional Chinese, Japanese, Korean, German, Spanish, French, Russian, Portuguese, Italian, Dutch, Polish, Turkish, Vietnamese and Indonesian. City names can use a different language from the interface.

Install

Dayside needs macOS 26 or later. Download Dayside-1.0.1-arm64.dmg for Macs with Apple silicon from the Releases page. An Intel package is not included in this release.

Open the disk image and drag Dayside.app to Applications.

The app is signed with a Developer ID and notarized by Apple.

You can find the version number in the app under Settings › Help.

Privacy

Dayside has no account, no telemetry and no ads. The release build has no network permission, and the app makes no network requests of its own. When you click a web link, it opens in another app, and that app may go online.

Your places, settings and saved records stay on your Mac. Dayside reads your calendars or contacts only after you allow it, and it does not change your contacts. The diagnostic log and crash reports stay local too. You can export a diagnostic report yourself; please read it before you share it, because it includes your saved places.

To report a security or privacy problem, see SECURITY.md.

Build from source

You need macOS 26 or later, Xcode 27, Rust 1.85 or later, Python 3 and the Rust Apple targets for the architectures you build. Cargo dependencies are pinned in RustCore/Cargo.lock. The commands below run offline, so those dependencies must already be in your local Cargo cache.

From RustCore/, run:

cargo test --locked --offline --all-targets
cargo test --locked --offline --release --lib
cargo test --locked --offline --lib --features intents-only
cargo clippy --locked --offline --all-targets -- -D warnings

From the repository root, check the license headers, localization catalogs and sharing page:

python3 Tools/spdx_headers.py --check
python3 Tools/l10n_check.py --check
node Tools/site_tests/when_test.mjs

The localization check covers source references and all 16 translations without a build. When compiler-extracted strings are available, it checks those too and reports that scope. Node is needed only for the sharing-page tests.

To compile the Mac app and its test bundle without running it, set DAYSIDE_DERIVED_DATA to a build-output directory, then run from the repository root:

xcodebuild -project Dayside.xcodeproj -scheme Dayside -configuration Debug \
  -destination 'platform=macOS,arch=arm64' -derivedDataPath "$DAYSIDE_DERIVED_DATA" \
  CODE_SIGNING_ALLOWED=NO build-for-testing

DaysideCore runs Tools/build_rust_core.sh to create the Rust static library before compiling Swift. Tools/sign_bundle.sh signs local builds ad hoc, so you do not need a developer account. Developer ID signing and notarization use Tools/release_sign_notarize.sh; the current download was signed and notarized with it. Tools/verify_all.sh also runs the Swift tests, which launch the app as their host. A build that succeeds does not show that the Swift tests or the app's interactions pass.

Where things are:

• RustCore/: rules, the city index, search, time reading, astronomy, planning, drawing geometry and saved data. See RustCore/README.md.
• Dayside/ and Shared/: SwiftUI views and Apple framework code.
• DaysideTests/, DaysideUITests/ and RustCore/tests/: tests and their fixtures.
• DaysideiOS/: an iPhone prototype that shares the Rust core, with fewer features.
• Tools/: build, test, packaging, measurement and data tools.
• site/: the page that opens a shared time card.

Dayside was called Meantime during development. Saved-data keys keep that name so settings from earlier builds still load, and many build and test variables still start with MEANTIME_.

Place names

City and administrative names come from GeoNames and Wikidata. Missing translations fall back to the recorded name.

Known issues

1. Automated accessibility checks pass on every page. A full hands-on VoiceOver walkthrough has not been done yet.
2. Market Clock includes the official 2026 holiday closures for Shanghai and Hong Kong. Other years follow general rules that can miss a bridging holiday. Half-day sessions are not shown.
3. Time zone rules come from macOS. Dayside warns when this Mac's data is older than known rule changes.

Feedback goes to GitHub Issues.

License

Dayside is free software under GPL-3.0-only. Every feature is free, and Dayside will never be sold. Copyright (C) 2026 Ninon. See LICENSE. Pull requests need a one-time CLA comment before merge.

Data sources and credits

• City data: GeoNames, CC BY 4.0.
• Place-name labels: Wikidata, CC0.
• Map relief: Natural Earth, public domain.
• Time zone rules: the IANA Time Zone Database that ships with macOS, read at run time.
• Day-period words: Unicode CLDR, Unicode License v3.
• The brush calligraphy on the Chinese welcome screen is made from glyph outlines of Liu Jian Mao Cao, SIL Open Font License 1.1. The epigraph lines are from Zhang Jiuling (Tang dynasty) and John Muir.

THIRD_PARTY_NOTICES.md has the details, and Dayside/Resources/ThirdPartyNotices.txt has the notices for the bundled Rust crates.