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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
4k 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
357 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
866 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
77 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
790 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
286 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
677 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
135 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
3answers
1k 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
309 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
95 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
238 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 ...
1
vote
1answer
303 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 ...
-3
votes
0answers
37 views

Should the Payment server be a separate server? [closed]

I am thinking of a web architecture for my project. My project is going to have a payment option. Should I keep the payment module within the same application project or should I make separate payment ...