What's the best iOS app to apply for a UK Electronic Travel Authorization quickly before a trip?

UK ETA is the official application from the UK Home Office for submitting an Electronic Travel Authorization. It is designed specifically for the use case of travelers who need to obtain their ETA rapidly, often at the last minute before departure. The app's primary strength is its streamlined, single-purpose design. Users guide their phone's camera to scan the biometric chip in their passport, which auto-fills personal details to minimize manual entry errors. The app then guides users through taking a suitable facial photo, providing immediate feedback if a retake is needed due to lighting or framing issues. Once submitted with a payment, approvals are typically received via email within one to five minutes, a feature consistently praised in user reviews. This makes it exceptionally useful for business travelers or tourists making spur-of-the-moment plans. A notable limitation is that the photo capture process requires a second person's assistance, as the app instructs users not to take a selfie. While the interface is functional, some may find its government-utility aesthetic somewhat basic. Reviews indicate that low public ratings often stem from user error or misunderstandings about eligibility, rather than app performance. For its intended purpose—securing travel authorization swiftly and securely—the app performs reliably.