MarginDiff — Supplier Feed Auditor + Margin Risk

Audit supplier catalogs before they break your product listings or cost you money.

MarginDiff compares CSV, TSV, or JSON product feeds, flags invalid SKUs/prices, detects low gross margins, and highlights suspicious changes between yesterday's catalog and today's. All processing runs inside an Apify Actor and produces exportable findings.

What it detects

Check	Issue code	Description
Duplicate SKU	DUPLICATE_SKU	Duplicate item identifiers (case insensitive)
Missing SKU/title	MISSING_SKU, MISSING_TITLE	Incomplete product records
Invalid/nonpositive price	INVALID_PRICE, NONPOSITIVE_PRICE	Unsafe product prices
Cost mistakes	INVALID_COST, NEGATIVE_COST	Bad supplier cost fields
Negative spread	NEGATIVE_UNIT_SPREAD	Unit cost greater than retail price
Low gross margin	LOW_GROSS_MARGIN	Margin lower than your threshold
Bad stock quantities	INVALID_STOCK, NEGATIVE_STOCK	Inventory data problems
Missing image	MISSING_IMAGE	No image field or empty image URL
Unexpected currency	UNEXPECTED_CURRENCY	Mismatched ISO currency value
Large price change	LARGE_PRICE_CHANGE	Price changed more than your threshold
Stock fall	STOCK_DROP	Inventory decrease beyond your threshold
SKU added/removed	NEW_PRODUCT, REMOVED_PRODUCT	Catalog changed since baseline

Quick start

Provide exactly one current feed source: a public HTTPS URL (currentFeedUrl) or pasted CSV/TSV/JSON (currentFeedText). Your feed must have at least a SKU and price column; a title, cost, stock, currency, and image column unlock additional checks. Common header synonyms are detected automatically.

Optional: provide an older version under previousFeedUrl or previousFeedText to enable change detection.

Example current feed

sku,title,price,cost,stock,currency,image_url
A-101,Adjustable laptop stand,39.99,17.00,20,USD,https://example.com/laptop.jpg
B-102,Desk cable clips,9.99,10.40,16,USD,

To check against a previous feed, paste a snapshot into previousFeedText or use the corresponding HTTPS URL. Set minMarginPercent to 20, and priceChangeAlertPercent to 25.

Outputs

Open Output → Issues for a searchable JSON dataset. Under Output → Reports, download:

• REPORT.html — visual audit summary and actionable findings.
• FINDINGS.csv — one row per finding, ready for spreadsheet review.
• FINDINGS.json — machine-readable issues for integration.
• SUMMARY — stats and parsed column mapping.

You can schedule recurring runs using Apify schedules. Each run compares the inputs provided for that run; MarginDiff does not automatically fetch yesterday's snapshot from a previous run. Your upstream system must provide or host the baseline for change detection. This avoids storing customer catalogs indefinitely within the Actor itself.

Pricing and limits

This Actor's creator chooses a price for one audit-completed event in Apify's Pay per event settings. A charge is attempted only after successfully auditing the feed. The default run accepts up to 10,000 products per feed; hard limit is 20,000. Text and public HTTPS downloads are capped at 8 MB each. No browser automation or paid proxy network is used.

Important: Publishing this source alone does not create monetization. The creator must enable the audit-completed event and set its price in Apify Console.

Privacy & safety

• Supply only catalogs you own or are authorized to audit.
• The URL downloader accepts public HTTPS feed URLs with valid certificates, pins a validated public IP address, blocks private/internal address ranges, rejects credentials and redirects, and imposes a 12-second timeout.
• Do not include customer identities, private tokens, passwords, or other secrets. Apify retains run input and output under its storage and retention policies.
• Data is not sent to a third-party AI service. No external telemetry or external APIs are called other than the optional user-specified feed URL.
• CSV output guards against spreadsheet formula injection.

Limitations

• A gross margin estimate does not include marketplace fees, shipping, returns, duty, tax, fulfillment, or overhead. It is not a full net-profit calculation.
• Monetary parsing expects dot decimal notation (19.99); comma decimals must be normalized upstream.
• The Actor checks field values but does not open image URLs or verify that every product is safe, sellable, or compliant with a marketplace.
• A public feed URL must resolve directly to a publicly accessible HTTPS resource; redirects, authentication, custom ports, and private networks are unsupported.
• When the previous feed contains duplicate SKUs, comparison uses the last occurrence of that SKU; remove duplicates before comparing.
• This is not a Google Merchant Center certification tool or a stock reconciliation with a live store.

Support and maintenance

Most weeks should require checking only run failures or user reports. If feed formats change, update aliases or use column overrides. Release updates after automated tests pass. Prompt handling of customer-reported issues is the creator's responsibility.

See PUBLISH_AND_PRICING.md for publisher setup. The program's core calculations can be tested locally without an Apify account: python -m unittest discover -s tests -v and python scripts/demo.py.