Interestingly, I happened to read about coinpayments.net a few minutes after I made this posting. So, I signed up and gave it a try, but I don't think it is what I am looking for, even though it is very close. I have not talked with anybody at coinpayments.net and maybe I am wrong about how it works, but I see 2 major problems with it:
Problem #1: Coinpayments.net quotes a list of estimated currency conversion prices at
https://www.coinpayments.net/supported-coins and I assume what they do is instantly liquidate the currency on an exchange (like Cryptsy.com) using an API. The problem is that when they create an invoice for the customer they base the conversion rate on the last sale price, which is meaningless for large transactions (like on my CheapFlowers.com site, most sales are $40-$100). To handle a $40 sale of Catcoin for example, their quoted price is 0.00001452 BTC (this is close to the last sale price at Cryptsy.com), but the actual price it would sell for on Cryptsy would go down to 0.00001220 because the quoted price is almost always for a very small trade amount (see the Buy bids in the order book at Cryptsy at
https://www.cryptsy.com/markets/view/136), which is a price 16% lower than what Coinpayments.net quoted the buyer on the payment page. So, it seems like for anything other than the top 4 or 5 most liquid altcoins, the merchant is losing out with this system. It is not that coinpayments.net is making money from this part, as their profit is only the .50% fee they charge, but it seems to be a bad deal for merchants. Nowhere on the site does it say exactly how the payments work in regards to the currency exchange, so I would think most merchants don't understand this risk. I don't think coinpayments.net is doing any of this on purpose, it is just how the site is setup, since any other way would be much much more complicated.
Interestingly, they give the merchant the option of providing their own wallet address for each cryptocurrency instead of having it go to coinpayments.net. They recommend using Cryptsy deposit addresses so you can use the Cryptsy auto-sell feature automatically sell any deposits that come in. That makes it much easier for the merchant, but still does not solve the currency conversion loss problem.
Since the Coinpayments.net site does not explain how the currency pricing conversions work, I decided to do an experiment. I used their merchant tools to create 2 test invoices, and then I tried paying them (like a customer would) using Catcoin:
$1 invoice - It told me to send 121.03556800 CAT
$100 invoice - It told me to send 12105.00575900 CAT
It is a little complicated to try to figure out the Coinpayments.net conversions, because just like Cryptsy does, they convert all the altcoins to BTC, but I used the current Bitcoin bid price from btc-e.com of $565.60 USD, and the Coinpayments.net quoted rate of 0.00001452 BTC for Catcoin and got these results of how much I would get as the merchant (before fees):
$1 invoice - $.9940
$100 invoice - $99.41
So, it seems like I am figuring out everything the same way coinpayments.net does, since both of the USD conversion rates almost exactly match the $ amount of the invoice. That is good so far, since it means they handle it exactly the way I think they do. Here's the problem with their system though. When I looked at the order book in Cryptsy, even to sell $1 of Catcoin had a much lower price than the last sale price, so here's what I would have actually received as a merchant through coinpayments.net:
$1 invoice - Cryptsy bid of 0.00001315 BTC = $.9002
$100 invoice - Crypsty bid of 0.00001220 BTC = $83.53
This is a problem because if I knew I was going to lose so much on the conversion, I would have quoted the customer a much higher rate. Coinpayments.net does have a feature that lets me charge a percentage extra for each cryptocurrency, but it would a lot of work for me to estimate the average markup I would need for each of the 52 currencies they offer, plus that markup is very dependent on the amount of the sale so there is really no way to estimate it.
Problem #2: The other problem with their system is they give the customer 4 days to pay the invoice. If the altcoin shoots up in value during those 4 days, the customer will cancel the invoice and not pay, but if it stays the same or crashes they will pay, so there is only downside risk for the merchant with fluctuating exchange rates. For comparison purposes, Bitpay.com give customers only 15 minutes to pay their Bitcoin invoice.
- Eric