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36
votes
1answer
2k views

Where does paypal's 92233720368547800 number come from? [closed]

There has been a story in the news about a man whose Paypal account was accidentally credited with $92,233,720,368,547,800. Where does this number come from? What sort of programming bug is likely to ...
8
votes
2answers
5k views

Handling subscriptions, balances and pricing plan changes [closed]

Preamble My aim is to create reusable code for multiple projects (and also publish it on github) to manage subscriptions. I know about stripe and recurring billing providers, but that's not what this ...
7
votes
5answers
359 views

What do you do to make the client understand that requirements not mentioned in contract should be charged separately? [closed]

I've done a very small project for a specified amount of payment. The project was some client-side validation code. However, now client asks for code improvement (general code improvement including ...
7
votes
3answers
981 views

Integrating with a payment provider; Proper and robust OOP approach

History We are currently using a so called redirect model for our online payments (where you send the payer to a payment gateway, where he inputs his payment details - the gateway will then return ...
4
votes
1answer
85 views

How does an product order payment works during a race condition?

This is a pretty generalized question which I am asking. Scenario 1 I have a product 'Pen' which has a quantity of 1. Now 2 users a and b has come to buy the product.User 'a' clicked on buy now and ...
3
votes
4answers
829 views

Freelancing - Getting paid for the quote or estimate [closed]

It is often necessary to spend time designing a solution, breaking down the design into tasks and sub tasks and estimating the time it will take to complete each task in order to produce a reasonable ...
3
votes
3answers
1k views

Should I ask for advance payment on custom work? [closed]

...for project-based work. So far I didn't, and always got paid when work was complete and didn't ran into any problems. Does this make me look unprofessional? :) Should I ask like 25% - 50% advance ...
3
votes
2answers
289 views

Using Paypal (or similar) to log into my site?

I have a web site and I want to offer a few levels of service - one free, one for a one-off payment, and one for a subscription. My first inclination is to use Paypal for the payment options. I ...
2
votes
2answers
745 views

How to overcome the fear of building a web application with a recurring payment system? [closed]

I'm a Ruby on Rails developer. I'd like to create a web application. I will let users get a payed subscription to use the product. So I will need a recurring billing system (e.g. via paypal). But ...
2
votes
2answers
142 views

Implementing a pay-per-user business model

Introduction I'm working on an application where organisations pay for each user they add to their 'environment'. Organisations have a credit/balance, and as long as the user is not removed, the ...
2
votes
1answer
91 views

Are hashed bank account numbers PCI data?

Background: I work for an NPO which receives large numbers of paper check donations every week. The current process of recording the donations is tedious and done mostly on paper. Because most ...
2
votes
1answer
257 views

How do I verify if 3rd party payment succeeded?

I'm working on a payment processing website that will function like PayPal does on many e-commerce websites. The idea is for the customer to fill their shopping cart and click checkout, then be ...
2
votes
3answers
2k views

Payment Gateways and RESTful API

I have a RESTful API that offers eCommerce functionality. One area I'm struggling to decide on the correct implementation is how to process payments. Lets say I have the following URI GET .../...
1
vote
5answers
313 views

Is there a way for developers and their clients to make a 'safety net' for the final transaction of software for money? [closed]

First off, we presume that the projects in question are not large or important enough for the parties involved to establish a formal contract, and that the parties are not able to meet in person. So, ...
1
vote
1answer
102 views

Is it correct to implement all the payment flow in the client rather than in the server?

I’m building a mobile app marketplace and I came to the point of integrating a payment tool. I'm using Mangopay, which has a nice workflow for making payments in a marketplace using its REST api. The ...
1
vote
1answer
333 views

PayPal proof of payment - is there a need to store it at our server?

I am developing an iPhone app, which I am integrating with PayPal. I did it successfully using PayPal library. I am testing it on sandbox mode. When I transfer money from one account to the other ...
0
votes
1answer
32 views

How do I handle the potential concurrency problem of making a payment to Paypal for a limited number of items?

After doing some investigation* I have learned that I could potentially have a concurrency problem. I'm currently building a Tournament Platform in ASP.NET MVC 5 with Entity Framework 6. So far, I'...
0
votes
3answers
107 views

Do you create an order before or after payment on an Ecommerce site?

I have a shopping cart with a checkout page. On the checkout page is a payment button which takes them to a stripe payment form. I've read some books on building eCommerce shopping carts in which ...