There are two routes to a UK ETA: applying yourself on the official site, and a professional agency that handles it for you. The authorization is the same, but the effort, cost and support differ.
Route A. Official site (gov.uk) — direct, cheapest
Applying directly via gov.uk/eta or the official "UK ETA" app costs only the £20 government fee Fact. It is the cheapest option, but you handle everything in English and resolve any errors yourself.
Common rejection reasons: typos in passport number or name, non-compliant photos (blurry, glasses, hat), mismatch between the application passport and the travel passport, and undeclared history Fact. There is no appeal if rejected, and the £20 is non-refundable Fact.
Route B. Professional agency (etaallpass.com) — convenient and accurate
If it feels burdensome, or you want to avoid even a single mistake, a professional agency is the answer. A service cost is added to the government fee, but in return you get convenience, accuracy and perks: filing in your own language, professional passport and photo review to pre-empt error-based rejections, 24-hour support, re-application and administrative-review help if problems arise, insurance/eSIM/airport fast-track bundles, and batch processing for families and groups.
Fact The final approval is decided by the UK Home Office on either route. An agency cannot guarantee approval either, but its core value is sharply reducing error-based rejections through professional review and staying with you to the end if problems occur.
Who should use what
Comfortable in English with time to spare → the official site. Want certainty without mistakes, family or group processing, and added perks → a professional agency.