Emerald Timestamp captures the precise time of events, and lets you associate a description with each one. It is also a highly-accurate running clock.

Very high precision:
- Uses atomic clocks via NTP, usually accurate to within 0.2 second
- Color coding (yellow and green) makes it obvious when you have a valid synchronization
- The network is required for synchronization, but you can record events without it with less accuracy
- When the app restarts, it uses the previous synchronization offset until the first sync comes in
- Version 2.0 and above display leap seconds in progress

Events are grouped by day in a scrolling list
- Record as many events as you like
- Add a description to any or all events
- Create multiple buttons with custom names to predefine event descriptions
- Easily show the difference in time between any two events

Easily cycle between time representations by tapping on a time in the display:
- Local 12-hour time
- Local 24-hour time
- UTC (aka GMT)
- Julian Date (JD) (settable globally to JD(TT) or JD(UTC))
- Interval from a reference time (using any event as a zero reference)

There is also a running clock at the top of the display showing the time in the chosen format.

You can use a hardware keyboard (such as the iPad Pro's Smart Keyboard) to trigger events using the space bar, enter key, or digits 1 through 0. [NOTE: if the keyboard is a bluetooth keyboard (unlike the Smart Keyboard which is direct connect) there will be a slight delay between the keyboard press and the time the app records.]

Email the time and description of an event, or all events (uses your device's email program), optionally using TSV or CSV for spreadsheets.

A complete description of each application feature can be found in the built-in Help screens and on the Emerald Sequoia LLC Web Site. A developer's blog may also be found at .

All date displays are localized, though the interface and Help are in English only.

If you are having any trouble with the application whatsoever, please see our FAQ on the support page listed below and then contact us through that page if your problem is not resolved. We take pride in responding promptly to all support email requests.

(NTP time synchronization requires network access. Like all other iOS apps, Emerald Timestamp cannot set the device's internal clock.)

What's New

Version 2.2.1

- Support for iPhone X
- Miscellaneous bug fixes

Ratings and Reviews

4.9 out of 5
8 Ratings
8 Ratings
Larrygps ,


Only thing that could make this better is iPhone hardware button trigger. (Like the camera app can use the volume up button to take photos.)

Almost no difference compared to GPS 1 PPS.

A nice piece of work. Great for astronomy. With iPod Touch one cannot set the device's time precisely. This app takes care of that.

Grey world ,

Simple, works great

Please keep up with updates. I have used this for many years!

Life in Truth ,

works well

Thank you. Any plans for a widget? I think that would be a nice to have.


Emerald Sequoia LLC
5.3 MB
Requires iOS 9.1 or later. Compatible with iPhone, iPad, and iPod touch.
Age Rating
Rated 4+
© 2010-2018 Emerald Sequoia LLC


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