If you purchase an item sold by Amazon and the price drops within 7 days, they will refund the difference. It used to be thirty days but too many folks took advantage of that. I quite like this policy, but I have to admit that I rarely ever go and check whether the prices of my purchases have dropped within a week. Since I have been exploring APIs lately, I decided this would be an excellent opportunity to work with Google's Gmail API. Combined with scraping Amazon price data, this makes it possible to automatically determine whether I am eligible for a refund. If this occurs, I will now be notified by email.

I broke this project into two sub-problems. First I extracted and processed all order confirmation emails that Amazon from my inbox. Next, I scraped the price data from Amazon for all items that were purchased within the last 7 days. This was slightly tricky since Amazon does not allow html requests without appropriate headers. In order to get around this limitation, I went into the developer console of my browser to extract the headers of "browser-based" html requests shown below.

GET / HTTP/1.1
Host: www.amazon.com
Connection: keep-alive
Cache-Control: max-age=0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/42.0.2311.135 Safari/537.36
Accept-Encoding: gzip, deflate, sdch
Accept-Language: en-US,en;q=0.8
Cookie: x-wl-uid=1KtoC6ENCLv2eHX1tihsendl3ViWKpTy60AyS+OYWZxDaGt9qmZCOsG+2k32zvX53cpgxM+EFETnycNMvCQZKbPXx3cT2Ywf7d1M45ElJn47uJiDdzUjUHxBFZUoOHY8OcAsePlQOPoY=; appstore-devportal-locale=en_US; x-main="nKZMwHi?WDeMPa56X4gnBq0ggtGfPTzT"; session-token="fgQpj6zW6t9FM/fI9himLeQ86HY7xo60p7kkwpQN3z3qVSeMvkA70ZNddjMgD4jKwAyfMNZK2l9qYhlcJcGLQbdJQGC4cxlHvEnFB7+BJw/fJ/OxCr3TVTnY/+9RK/Vh/bmJ49RT0LyzBiRoLFYDUuOQG/9PDrlb1govpLGWEM0MQE0bVNUzwfEYHa+Q+/uznlz9yWDMxv9k5+fZ0T4bMw=="; s_cc=true; s_fid=0D00BCD6130993FC-2911D224B6E21834; s_nr=1431213418630-Repeat; s_vnum=1433142000856%26vn%3D2; s_sq=%5B%5BB%5D%5D; skin=noskin; b2b-main=0; csm-hit=s-0EVGT30S70BV35R4Q186|1431465081867; ubid-main=188-8202718-7770715; session-id-time=2082787201l; session-id=190-6280221-3660231

After attaching these headers to my Python requests, Amazon happily complied and send their data my way. Every 12 hours my program loops and checks for price updates. Source code can be found on my Github account.