KYC API Integration Patterns That Inflate SaaS Bills — and How to Fix Them

Short summary

A practical guide on how naive KYC API integrations can inflate SaaS bills by 2-3× due to per-attempt billing models and user retry loops. KYC vendors like Veriff bill per submission, not per success — with 30-50% failure rates in fintech, uncontrolled retries can cost $4+ per rejected user. The article prescribes client-side pre-validation (resolution checks, local OCR for expired docs, input masking), a strict PostgreSQL state machine to cap retries and prevent duplicate charges, and safe webhook handling with row-level locking.

• •KYC vendors often bill per attempt, not per success — 30-50% failure rates can double costs
• •Client-side pre-validation (resolution, OCR, regex) prevents billable API calls on obviously invalid documents
• •A strict PostgreSQL state machine with retry caps and row-level locking prevents duplicate charges from race conditions

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