
sicherheitshalber
just in case
Out of caution and in order to be on the safe side; to avoid a possible risk.
Ich habe die Daten sicherheitshalber auf einer externen Festplatte gespeichert.
I saved the data on an external hard drive just in case.
just in case
Loading your saved state.

just in case
Out of caution and in order to be on the safe side; to avoid a possible risk.
Ich habe die Daten sicherheitshalber auf einer externen Festplatte gespeichert.
I saved the data on an external hard drive just in case.
The word is made up of three parts: 'Sicherheit' (safety/security), the linking 's', and 'halber'. The ending '-halber' means 'because of' or 'for the sake of'. Literally, it means 'for the sake of safety'.
Nimm sicherheitshalber einen Regenschirm mit.
Take an umbrella with you just in case.
As an adverb, 'sicherheitshalber' (just in case) can stand at the beginning of the sentence (position 1), followed by the verb. It can also stand after the verb in the middle of the sentence.
Sicherheitshalber habe ich die Tür zweimal abgeschlossen.
Just in case, I locked the door twice.
'Sicherheitshalber' (just in case) is often connected with actions meant to minimize a risk. Typical examples are: taking something along, checking something, making a copy, or leaving earlier.
Wir sollten sicherheitshalber eine Stunde früher zum Flughafen fahren.
We should leave for the airport an hour earlier just in case.
precautionary
Both words refer to an action taken against a possible risk. „Vorsorglich“ emphasizes forward-looking, planned prevention, while „sicherheitshalber“ highlights taking a specific extra safety measure in a particular situation. Use „vorsorglich“ for the measure and „sicherheitshalber“ for the additional step taken to be on the safe side.

Die Schule sperrte den Spielplatz sicherheitshalber auch am nächsten Morgen.
The school also kept the playground closed the next morning, just in case.
Die Schule schloss vorsorglich den Spielplatz wegen des angekündigten Sturms.
The school closed the playground as a precaution because a storm had been forecast.