Most Chrome extensions that need data fall into one of two patterns: they call an external API, or they store a small amount of user-specific data locally. EntryCheck does neither. It bundles a static dataset of visa requirements for 190+ passport/destination combinations directly into the extension and resolves every lookup client-side with zero network requests.
This tradeoff — large bundle, instant lookups, no API dependency — turns out to be the right call for travel data. Here's why, and how it works.
Why Static Over API
Visa requirements don't change often. A country might update its visa-on-arrival list two or three times a year. An API would add latency, require authentication, and create a failure mode (network unavailable, API down, rate-limited) in a context where the user is typically trying to quickly check something before booking a flight.
More practically: there's no reliable free public API for visa requirements. The data sources are government websites and reference databases. Scraping or licensing these for a real-time API isn't worth it for a tool whose value is speed and simplicity.
