Receive Payment BEFORE an Invoice has been created - payment

I am trying to make a link on my website that allows a customer to pay us money for a task we will be working on for them. I have looked through Intuit's/Quickbook's developer website and articles, and I have to say they are not much help. Currently I'm not sure if I am going to have to create an app that uses some sort of web connector, of if I can just get a link from my account somewhere, or create a webpage that just connects to Quickbooks.
Has anyone here done this before, and if so is there any direction you could point me in? I've tried asking on their forums & support forms but have yet to receive any response.


Paypal, angular 2 and expressjs server

I am new to web development and have put together a decent Angular 2 MEAN web-app that I would like to launch relatively soon. Unfortunately PayPals documentation is such a gigantic Kafkaesque clusterf maze swamp mire that I am lost in and have no clue what I'm doing, I have 30 browser tabs open including code examples and their node sdk/REST. I've tried a few of the different options on offer which involved pasting their scripts to try get a button but nothing happened. Does anyone have a simple guide I can follow and a simple recommendation for integrating paypal payments into MEAN stack? I just need to be able to set payment amounts based on data that is contained in objects I have access to in my front-end, so a simple front-end solution would be nice where user can pay with paypal account or credit card and where I can plug the variable {{event.price}} straight into paypals api and send it off, and verify it somehow.

How to Integrate PayPal Functionality into Desktop Application

Sorry if this is a possible duplicate, but I've searched around quite a bit and couldn't find anything that helped me understand how to achieve what I want to do.
Also, I find the PayPal API documentation confusing.
This is my usage scenario. The desktop application is coded in C#.
1 - I have a Desktop application, I want to add a "Shop" button which will open up a shop interface. In the shop interface they can choose from "packages" I have set up.
2 - When they click "Purchase", I want to open the appropriate PayPal page in their default browser. In this step I also need to send PayPal additional information(such as the User ID and Package Number)
3 - When they complete the purchase through PayPal, I would like PayPal to send a notification to my desktop application, returning the additional information I supplied (User ID and Package Number), as well the the Purchase status (i,e complete, pending, etc).
So basically, what I need to learn is;
How to send PayPal additional information when directing the user to the appropriate PayPal page on the default browser(done in the desktop application).
How to get PayPal to send a reply to my desktop application when the purchase is completed. (The reply should contain the additional information supplied, and something like a "purchase status")
I'm not asking for code, but code examples would be appreciated.
I just haven't been able to understand/find how to accomplish this, if it's even possible. I want to stay away from any web related approach, because I know absolutely nothing about web development.
PayPal have a .Net API with documentation that should help you out.
API Repository:
Edit: The repo has a samples folder with .Net solutions that you can look at.

PayPal Intergration

Am I the only 1 who is confused by PayPals developers info?
I have a website. I want the User to be able to click the PayPal icon and when they made a payment the payment notification is sent to my URL.
I have created a button for this but I want the notification of payment to be sent to one of my URLs.
I also want to test this using a sandbox account. But after creating the sandbox account and I click 'create button' on the developers website it redirects me to the 'live' paypal website where the construct of the button is as it was before.
I created a sandbox account and I have the criteria details.
Yet, despite many hours Googling i cannot find a simple easy to understand C# example of what I want to do. 1 minute i am looking at their developers BETA web site, the next I am looking at an example code on CodeProject that is 4yrs old and not replicated in any of the examples I can see elsewhere.
Someone please help?
Please do no send links to PayPal as I have gone through them all.

How to Process Credit Card Purchases Through C# Web Service

We are designing an iPhone app for a client and need to create a store front where users make purchases. I have everything figured out about the app, except how to process the credit card information from the users. The client we are doing this for has a server running Microsoft RMS, which he uses to process orders from his website and stores as well.
Any ideas how we should pass the purchases from the iPhone to the server? (we are designing the server side in c#) And any ideas how our client may be processing those payments now, so that we can integrate easily with their systems? (he uses Microsoft RMS)
Thank you!
This question has been asked and answered more times than I can count.
( How can I bill within an application )
In addition to that information, you should also check out:
Which talks specifically about a MS RMS approach.
I believe you can setup RMS to import records from a SQL database... which I'd look into, because I think that it will be a lot easier for you to process the transactions in .NET directly through your gateway of choice, and batch the resulting records for import into the RMS system.
This company claims to offer a product that might make your life easier, but i've never used it, or heard about it before now:
Ditto with this one:
Otherwise, regarding iPhone <--> Server, I'd suggest you check out setting up a WCF service which uses JSON.... or look into the objective c soap client proxy generators.... but, honestly, JSON is just much much easier to deal with on the iPhone.
Copy of my answer from the other thread:
There are lots of ways to go about setting up e-commerce sites;
If you don't have any experience whatsoever, and don't want to get into anything "complicated", i would suggest going with a customizable web "storefront" hosted by someone else, pre-integrated with credit card processing, etc. There are tons of options for these online. Just search google for "web storefront". Yahoo! even has such a service:
Going beyond that, It's pretty easy to integrate with someone like PayPal. They have all sorts of options from the most basic (use a link to send someone to their site with query string parameters to let paypal know what the user wanted to buy):
Beyond that level, you will need to signup for a merchant account, or other similar sort of service, like the one offered by (who I like):
There are components you can buy for most major web development platforms like .NET, JSP, etc. Perfect example is dotnetcart. These components provide out-of-the-box, easy-to-setup integrations with major CC processing companies, as well as out-of-the-box shopping cart implementations:
Finally, most merchant services / payment gateways provide web services for direct integration.
PS.) Never ever ever store CC numbers ; )

Login to online accounts

First time poster. Back to programming after being away for a few years, trying to clean off the rust. I'm creating a dashboard that will run initially on my laptop (Macbook Pro, 10.4.x O/S). Amongst other things I want it to retrieve latest information from my online accounts. I'm starting with html, but will probably migrate to something else (TBD, possibly ruby or c#). What would sample code look like for logging into account, going through specific account workflow, retrieve data/docs/other, and pull it back to be stored locally.
It is a little open-ended, apologies and thanks in advance.
Are you looking for something like Google Gears?
It depends on the kind of accounts you want to log onto.
For instance there is a Google has an specific API for that Google Accounts API, other services provide similar API's some other do not.
So it depends pretty much what are your "online accounts" all about and if they do provide a public API or not.
As per your comment and for the products you've mentioned, I'll suggest your to start looking at browsers plugin development and to start understanding the HTTP protocol and all the related technologies around it ( HTTPS, encryption, authentication etc. )
The public API let you easily login into an account, but you don't really need one to do it ( although it make life much more simpler ) If you do not have a public API, you can still login into any account by "simply" doing what the browser does. Sending an HTTP(s) request with the appropriate security mechanism and following the protocol.
If you know how does the browser send the request and you have the user trusting your their passwords, the only remaining thing you have to do is ... :) code it.
As of now the question is too broad to be answered. Pick one service at a time and ask specific questions about it.
I would suggest you to start with the previously mentioned "Google Accounts" API and learn from there.
One open source product that already manages google account authentication is "Ubiquity" you can take a peak at their source code and start understanding how do they fetch the user contact list.