Instant payment notification for a merchant?

[Mark Oates]

Here's the concept:  I create a website where a digital good can be purchased by a scan of the QR code.  The user wants to buy the product, and sends money to the address.

instantly (e.g. "instantly"), that div where the QR code is located is replaced with a link to download that product.

I'm looking for a payment processor or service that can provide validation as quickly as possible.  I would be willing to accept the downside in the event that the payment is not fulfilled, for example 1 confirmation that is later oops no confirmations for the advantage of speed.  So, some provider that can receive the payment, validate it as quickly as possible, and send a notification.

I can do all the programming on the back end, but what I need is that instant notification (as "instant" as possible anyway).

Off the top of my head, I could scrape blockchain.info every 3 seconds or something... that seems expensive and unnecessary.

Any help?

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[em3rgentOrdr]

I am actually trying to implement instant downloads also.  I have investiaged many options, and I beleive the best and freest way involves opening up a websocket to blockchain.info via their api (http://blockchain.info/api/api_websocket) and tell it to listen for notifications for whenever there is a transaction to your address.  Then it is just a matter of providing a secret download link for a particular ip addresses or account.  But again I'm still trying to implement this, so please let me know if you have any ideas or luck.

Currently I am using the blockchain.info Receive API (http://blockchain.info/api/api_receive) but it takes like 10 minutes for blockchain to send confirmation.  I modified their example program...You can try my test link: http://efjz.in/?d=test.mp3

[john_doe]

Currently I am using the blockchain.info Receive API (http://blockchain.info/api/api_receive) but it takes like 10 minutes for blockchain to send confirmation.  I modified their example program...You can try my test link: http://efjz.in/?d=test.mp3

That is not quite correct. The API invokes your callback URL when it receives the payment (i.e. 0 confirmations) and then keeps invoking your callback URL for every new confirmation (1, 2, 3, ...). It will stop doing this when you acknowledge the callback (I think you need to return the string "*ok*" or something like that). So this is perfect for zero-confirmations payments.

[em3rgentOrdr]

Currently I am using the blockchain.info Receive API (http://blockchain.info/api/api_receive) but it takes like 10 minutes for blockchain to send confirmation.  I modified their example program...You can try my test link: http://efjz.in/?d=test.mp3

That is not quite correct. The API invokes your callback URL when it receives the payment (i.e. 0 confirmations) and then keeps invoking your callback URL for every new confirmation (1, 2, 3, ...). It will stop doing this when you acknowledge the callback (I think you need to return the string "*ok*" or something like that). So this is perfect for zero-confirmations payments.

Actually I do send the *ok* confirmation when blockchain.info sends a callback with 0 confirmations, but still take 1-10minutes (I see this in the log).  Same if I go though the shared wallet (which is protected against doublespending at 0 confirmations).  I have the browser's page be redirected to a page ready2download.php that refreshes every 10 seconds until this 0th confirmation is received, at which point that page turns into an file download.

[Tungsten]

I've built wordpress plugin for WooCommerce that utilizes blockchain.info API. It worked as described back in December 2012 and then suddenly they (blockchain.info) changed something on the backend.
As a result - you get quick notification of first transfer (with notifications=0): client -> temporary address
But then you'd have to wait for *days* until funds will get to your main merchant address: temporary address -> your wallet address
I explained that here:
http://wordpress.org/support/topic/note-why-payment-notifications-may-be-slow

I opened few support tickets with blockchain.info, received one reply and then dead silence. One user of plugin still haven't received payment back after 4 days.
This pisses people off and especially me as a developer of a bitcoin payment solution. I promised people a working solution and they got shit.
People don't care if that's a blockchain.info fault or my fault, but that's not how payments (no matter how open sourced they are) should operate.

So right now I am working on much superior and secure product - Bitcoin Payments version 2.x for Wordpress that will not require any third party services (besides polling blockchains for confirmations). Hence more predictable, reliable and secure (no private keys needed anywhere).

It will utilize Electrum wallet's Master Public Key to securely generate unique addresses to receive payments and funds will automatically be reflected inside merchant's deterministic wallet. It will poll blockchain for notifications automatically and process "Order fullfilled" as soon as desired number of notifications is reached. It could be zero and it could be instant.
In fact I love how blockchain.info immediately "beeps" when I get transfer from MtGox or anywhere.

Anyways, I do believe that the best solution will have the least amount of middlemen (and snoops) to feed and least amount of potentially broken links to support, and working on it.

Stay tuned - soon you'll be able to build cool, professionally looking, secure online stores, supporting Bitcoins as well as any other currencies simultaneously without paying percentages or fees to any middlemen.

Gleb
http://www.bitcoinway.com/

[john_doe]

Sounds like a very good solution. Except that you will be tied to an Electrum's wallet 

[ron_]

if you don't want to be tied to a wallet try :
https://btcipn.com/
it's already being used by some guys

[Tungsten]

I just updated bitcoinway plugin to WooCommerce.
Download page is here:
http://www.bitcoinway.com/products/

Number of bugs are fixed.
Bitcoinway plugin for woocommerce allows anyone to launch online stores and sell physical and digital products charging customers in bitcoins as well as in any other worlds currency.

All purchases are automatically gets deposited into your own electrum wallet.

Main advantages:
- no middlemen or extra service involved.
- you are not paying any fees to anyone or losing percentages of your sales.
- 100% security: bitcoinway - based store are impossible to hack. There are no private keys needed or used anywhere. Even if hacker takes over your server, database and all files - he cannot steal any funds. Your bitcoins are absolutely safe and after each purchase are  immediately arrive to your own, private wallet.

Enjoy!

Gleb

[MrNiceGuy22]

This free service sends you a text or email when your bitcoin transaction has been confirmed:
http://BSIPro.com/bitcoin