Extract Line Items from Invoices

Turn PDF invoices into structured JSON line items you can validate and post to accounting.

Request json output and read line items from blocks
Parse descriptions, quantities, and prices into clean records
Validate subtotal, tax, and grand total in Python

Time to complete: ~15 minutes

Prerequisites

A SAGEA_API_KEY exported as an environment variable
An invoice file in PDF, PNG, JPG, TIFF, or WEBP format, max 100MB, ideally 300 DPI
Python 3.9+ with the requests package installed
Set up document processing
ARVA OCR model card

Step 1: Send the invoice to ARVA OCR

Request output_format="json" so you get text, pages, confidence, and blocks back.

curl -X POST https://api.sagea.space/v1/ocr/process \
  -H "Authorization: Bearer $SAGEA_API_KEY" \
  -F model="arva-ocr" \
  -F [email protected] \
  -F output_format="json"

Expected JSON shape:

{"text": "...", "pages": 2, "confidence": 0.992, "blocks": [{"type": "paragraph", "page": 1, "bbox": [x0,y0,x1,y1], "confidence": 0.99, "text": "..."}], "model_used": "arva-ocr"}

ARVA OCR reaches 99.2% accuracy on clean scans. Standard pages cost $1.00 per 1000 pages.

Step 2: Parse blocks into line items

Filter blocks for line-item rows and convert them to dictionaries.

curl -X POST https://api.sagea.space/v1/ocr/process \
  -H "Authorization: Bearer $SAGEA_API_KEY" \
  -F model="arva-ocr" \
  -F [email protected] \
  -F output_format="json" \
  -o invoice.json
cat invoice.json

Step 3: Validate totals before posting

Recompute subtotal and grand total and compare against the extracted total.

import re
 
full_text = data["text"]
m_total = re.search(r"Total\s*\$?([\d,]+\.\d{2})", full_text)
m_tax = re.search(r"Tax\s*\$?([\d,]+\.\d{2})", full_text)
claimed_total = float(m_total.group(1).replace(",", "")) if m_total else None
claimed_tax = float(m_tax.group(1).replace(",", "")) if m_tax else 0.0
 
subtotal = round(sum(i["line_total"] for i in items), 2)
computed = round(subtotal + claimed_tax, 2)
print(f"subtotal={subtotal} tax={claimed_tax} computed={computed} claimed={claimed_total}")
 
assert claimed_total is not None, "no total found in OCR text"
assert abs(computed - claimed_total) < 0.01, f"total mismatch: {computed} vs {claimed_total}"
print("totals balance - safe to post")

Verify

Error	Cause	Fix
`401 Unauthorized`	Missing or invalid API key	Export a valid key as `SAGEA_API_KEY` and retry
`400 unsupported_format`	File type not in PDF, PNG, JPG, TIFF, WEBP	Convert the invoice to PDF or PNG and retry
`413 Payload Too Large`	File is over 100MB	Compress or split the PDF, then retry
`429 rate_limit_exceeded`	Too many requests at once	Back off with retries and reduce concurrency