Python Developer — Amazon Product Validation Fallback

Overview

We run a fintech app that validates Amazon products before purchase using Zinc's offers API. Zinc has been throwing intermittent 500s, and we need a reliable fallback using SerpApi's Amazon Product API (engine=amazon_product).

This is a focused integration into an existing Python codebase — not greenfield. You'll follow established patterns and work closely with our team.

Scope

• Codebase analysis (before any code is written)

Review our current Zinc integration — offers API usage, validation logic, caching layers, retry behavior, and DB fallback flow. Document how each validation field is sourced and used in the purchase decision.

• SerpApi client

Build a client that calls /search?engine=amazon_product&asin=[asin], handles errors/timeouts, and follows our existing service patterns.

• Response mapper

Translate SerpApi's purchase_options.

buy_new into our existing offer validation format:

• stock == "In Stock" → available
• Determine how to reliably identify new-condition offers from the response structure
• Delivery date strings (e.g. "FREE delivery Wednesday, December 24") → handling_days_max (requires regex + year inference)
• FBA inferred from delivery text ("shipped by Amazon", Prime mentions) — no boolean available
• extracted_price (float) → integer cents
• Field mapping document

A clear table:

each Zinc field we validate → equivalent SerpApi field → parsing approach → known gaps or limitations.

• Fallback hook

When Zinc fails and our DB cache is stale, call SerpApi before giving up on the product.

• Tests

Unit tests covering:

happy path, out-of-stock, non-FBA, delivery parsing edge cases, and API error handling.

Tech stack

Python 3.8 · Tornado · SQLAlchemy · PostgreSQL · Redis

Key challenges worth calling out

Delivery date parsing:

SerpApi returns human-readable dates with no year — you'll need regex and year-boundary inference.

FBA detection:

No structured boolean from SerpApi — must be parsed from delivery/seller text.

Contract duration of less than 1 month.

Mandatory skills:

Python, SQLAlchemy, Tornado, PostgreSQL