사확 (Sahwak)

Overview

사확 (Sahwak) is a Flutter mobile app that verifies Korean business registration numbers (사업자등록번호) directly against the 국세청 (National Tax Service) public API. Enter a 10-digit number and get the registration status (계속사업자 / 휴업자 / 폐업자), tax type, closure date and other information.

The name 사확 is the canonical Korean abbreviation of 사업자확인.

Features

• Instant status lookup — calls 국세청 직접 via the data.go.kr public API
• 진위확인 (Authenticity check) — Pro feature that cross-verifies the registration number against the representative name and opening date
• 통신판매사업자 lookup — pulls FTC online-mall seller data for e-commerce due diligence
• OCR scan — recognize a business number from a 사업자등록증, 명함, or 영수증 photo, fully on-device via Google ML Kit
• Batch verify + CSV / PDF export — Pro feature for bulk lookups
• Local-only history — verifications and favorites stored in SQLite on device; nothing is sent to a developer-operated server
• Korean + English UI

Pricing

Free tier covers 5 verifications per day, extendable to 15 with voluntary rewarded ads. Pro is a one-time ₩4,900 unlock — 100 verifications/day, ad-free, and unlocks 진위확인, batch, OCR, CSV/PDF export, and unlimited history. No subscription.

Privacy

The app runs no server of its own. Verification queries go directly to 국세청 / FTC public APIs; everything else stays on the device. See the privacy policy for full detail, or the data deletion guide for instructions on removing your data.

Tech

• Flutter with Riverpod 2.0 for state and DI
• Drift (SQLite) for local history with reactive queries
• Dio with retry and certificate pinning for the public-API client
• Freezed for typed entities and use cases
• RevenueCat + AdMob for monetization
• google_mlkit_text_recognition for fully on-device OCR

Published by Bassarisk Studio.