What you are actually trying to prove
Before choosing a method, separate two questions. First, did the worker arrive and leave at the times claimed? Second, did they remain on site for the duration? A QR code scan answers only the first, and only weakly: it shows a phone was near the sticker at that moment. It says nothing about the next four hours.
If your client disputes a timesheet, or a worker disputes a deduction, you need evidence that holds up when challenged. That means a continuous record, not a single tap. The alternatives below differ in what they record, how tamper-proof they are, and what they cost to run.
GPS location trails
GPS is the most direct replacement. The phone logs a position every few minutes, and software derives a visit from time spent inside a geofenced boundary. You get an arrival time, a departure time, and a duration without anyone tapping anything.
What it proves: the device was inside the boundary for the stated period. That is stronger than a scan, but it is not proof the person held the phone. A worker could leave the phone in the site office and walk off. In practice, most field workers carry their phones, but be aware of the limit.
Where it fails: deep indoors, under heavy cover, or in urban canyons, accuracy drops. A good system marks readings it does not trust, rather than silently guessing. You should be able to see the raw trail and the confidence level for each point.
Beacons and BLE tags
Bluetooth Low Energy beacons placed at site entrances or key areas. The phone detects the beacon's signal and records proximity. This is more precise than GPS inside buildings and uses less battery.
What it proves: the phone was within a few metres of that beacon at that time. It is closer to a QR scan, but it can be continuous: the phone can log when it enters and leaves the beacon's range, giving you a duration.
Limits: beacons need installation and battery replacement. Signal can bounce off walls, causing false readings. Also, a worker could carry a second phone that stays near the beacon while the real phone leaves. Rare, but possible.
Worker selfies with time and location
A photo of the worker at the site, stamped with time and GPS coordinates. Some systems add a live background check or a random prompt.
What it proves: the person was at that location at that moment, assuming the photo is not edited. It is a stronger identity check than a QR scan, because it ties a face to the record.
Limits: it is still a point-in-time check. It does not prove the worker stayed. Also, privacy concerns: workers may object to routine photos. Use it as a supplement, not the whole system.
Wi-Fi and cellular network presence
Some systems use the phone's connection to known Wi-Fi networks or cell towers to infer location. This works where GPS is unavailable, such as basements or steel-framed buildings.
What it proves: the device was within range of that network. Accuracy varies with network density. In a rural site with one mast, you might only prove the worker was within a few kilometres, not on the site.
This is best as a fallback, not a primary method. Combine it with GPS or beacons to fill gaps.
Comparing the options on cost and effort
QR codes are cheapest to set up: print a few stickers. GPS trails cost nothing per site but require a phone app and a data plan. Beacons cost hardware and maintenance. Selfies cost nothing but create privacy friction.
For a single-site crew of five, QR codes may be enough. For a client who disputes hours weekly, or for a multi-site operation where you need to prove route coverage, GPS or beacons pay for themselves in avoided arguments.
Also consider the audit trail. A QR scan log can be edited after the fact unless it is sealed. Look for a system that appends changes, keeps the old value, and hashes each day's data so you can prove it was not altered.
When QR codes are still the right choice
QR codes are not useless. They are ideal for low-stakes attendance where the main goal is to stop obvious abuse, and where workers already have phones. They also work offline, which matters on remote sites with no signal.
Choose QR codes if: you only need a start and end time, there is no history of disputes, and the site has no power or connectivity for beacons. Choose a location trail if: you need to prove duration, you face audits or legal challenges, or you manage multiple sites and need to verify route coverage.
The honest answer is that many operations use a combination: QR for entry, GPS for duration, and a selfie for identity on high-risk sites. The key is to know what each method proves and to pick the one that matches the level of proof your clients demand.
Questions
Can GPS prove a worker was actually on site?
GPS proves the phone was inside the boundary for the time period, not that the person held the phone. It is stronger than a QR scan because it covers the whole visit, but it cannot rule out a worker leaving the phone behind. Combine with a check-in selfie or random prompts to close that gap.
Do beacons work outdoors?
Yes, but range is short, typically 10 to 30 metres. They are best for entrances, gates, or specific work areas. For a large open site, GPS is more practical. Beacons also need maintenance, so factor in battery changes.
What if a worker has no phone signal?
GPS works without cellular signal as long as the phone can see satellites. The phone stores the trail and uploads it later. QR codes also work offline. Beacons need a phone to receive the signal, but no internet connection at the moment of detection.
How do I stop someone from editing the attendance log?
Look for a system that is append only: any edit keeps the old value with a name and timestamp. A daily hash seal means if any stored value changes afterwards, the day no longer matches, and you can demonstrate the log was not altered. Avoid systems that let you silently correct entries.
Which method is cheapest to run over a year?
QR codes are cheapest to set up but have no continuous evidence. GPS trails cost nothing per site beyond the phone app and data, but require a subscription for the software. Beacons have hardware and battery costs. For a small team with no disputes, QR is cheapest. For larger teams or regular disputes, GPS often saves more in avoided arguments.