App for Android and IPhone: geotagging, image stamping

[Peter2]

For usage in my office (field work) I'm searching for an app for mobiles which should ..

- add the GPS data to the image data (EXIF)
- write the GPS data to the image ("Stamping", "watermark")
- also write (stamp) free defined text to the image
- write the free text to EXIF and/or IPTC data
plus
- should be stable
- should be trustable, does not share data or upload something to somewhere
- should work on iOS and Android

Looking to the app-stores there are tons of results, but are there some apps which are really recommended?

[xnview]

could you please contact me by email