Load your GPS track (with timestamps), then add your JPEG photos. Each photo is matched to the nearest track point by its capture time and gets GPS coordinates written into it — then downloaded. If the camera clock is off, nudge it with the fine offset. Your photos stay on your device; nothing is uploaded.
FAQ
Are my photos uploaded?
No — reading EXIF and writing GPS happens entirely in your browser. Only the track (non-GPX) may be converted server-side.
Which photo formats?
JPEG. For RAW, HEIC or video use the free Reisezoom desktop app.