From Regex Hell to AI: How I Finally Tamed Messy PDF Invoices

Short summary

Developer switched from regex/OCR to LLM-based PDF invoice extraction with JSON schema validation, achieving 95.6% accuracy (478 of 500) in 45 minutes versus three days of manual work. Cost: ~$10 total at $0.01-0.02 per request. Key tradeoffs: 2-4 second latency, hallucinations, prompt sensitivity, data privacy concerns when sending sensitive documents to external APIs.

• •Replaced regex/OCR with LLM API + JSON schema for invoice data extraction from unstructured PDFs
• •Achieved 95.6% accuracy (478/500 invoices) in 45 min vs 3 days of manual work, cost ~$10 total
• •Tradeoffs: 2-4s latency per request, hallucinations, prompt sensitivity, GDPR/data privacy risks at scale

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