Ask anything to PayPal Developers

PayPal operates a worldwide online payments system that supports online money transfers and serves as an electronic alternative to traditional paper methods like checks and money orders.

This is AMA with great minds developing PayPal APIs like Express Checkout, PayPal Payments Standard, In-Store, Marketplaces, etc.

Ask PayPal Developers about:

  • PayPal APIs
  • PayPal OSS
  • Mobile Payments Integrations
  • Working at PayPal
  • NVP/SOAP API SDKs
  • PayPal REST SDKs

Hosted by:


Hello Hashnode folks! We're super excited to be here for this AMA session 😀

The host team is a broad representation of engineering, professional services and management at PayPal, so we can tackle pretty much any question you throw at us.

We're more than happy to discuss our engineering practices, open source work, mistakes from the past and lessons learned, corporate culture at PayPal, "day-in-the-life" questions, our diversity and inclusivity initiatives and more!

Only a couple of topics are off-limits (Legal said so...). We can't give any forward looking statements on company performance, and obviously we can't give away "secret sauce" information.

Looking forward to answering everyone's questions!

-The PayPal Team.

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85 discussions

Hi PayPal Devs! It's amazing to see you all going live publicly for the first time (I guess) 😀

How does PayPal write test cases? I mean one single mistake and you can end up having huge loss! 👀

Without going into the details, if you can just explain briefly what goes under the hood, it will be really helpful.

Hello. Thanks for your question. You are right. We do invest considerable time of developers into testing. For front tier we do not have dedicated testing teams. Developers are expected to write and maintain tests for their code. For node.js, we use some awesome open sourced modules on npm like jest, tape, mocha, jasmine(and many many more). Teams have their own freedom to explore on this front. For functional testing in browser, we have our own opensourced framework nemo.js (https://github.com/paypal/nemo). I've seen some teams use Phantom.js.

We do have full fledged Quality Assurance teams for testing Service infrastructures and full end-to-end testing of a product. We have specific environment setups for pre-build developer checks, Build check before release, and we have a Sandbox environment that mimics Production code to test without having to move money from our account and buying stuff online in the name of testing ;) :p

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What’s the code review process in PayPal like?

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Our team's code review process is mostly similar to Kent Dodds. We take advantage of GitHub's Pull Request Templates to ensure our developers fill in the right details of their change. These vary across projects, but generally include:

  1. Problem
  2. Solution
  3. Verification (screenshots, or steps the submitter did to reproduce the issue)
  4. Concerns
  5. Relevant links
  6. Required reviewers

Naturally some changes don't require this much paperwork, and only number 1, 2, are 6 mandatory. For simple or focused projects, we may require only one code reviewer.

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Hello, Paypal devs. It's nice to see you here. I welcome you to the Hashnode DEV community.

Can you please give provide little details about PayPal's tech stack?

Thanks for AMA.

Hello :wave:

Core Paypal's stack is potentially slightly different than the subsidiaries and acquired companies. At Paypal, for the web-tier we completely moved to node.js in the past 3-4 years. In the client, we have quite some freedom to explore frameworks of our choice (Angular, React, ... even the old timer Backbone in a few cases). For mobile native, the Paypal App uses swift on iOS and Java-Android. For one of our checkout SDKs (which is an effort I am leading currently), we have been exploring using react-native. In the mid-tier we mostly write Java services. A few orchestration services use node.js as well. There are even a few legacy systems using C++. For analytics, we use PIG for mining flat data alongside Hadoop and SQL scripts for db sourced data.

For a big company, we take pride in moving fast to explore newer technologies. At the same time, as a big company, it takes time to deprecate older stacks due to the humongous effort involved :))

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Thank you PayPal folks for doing this AMA. I have three questions.

  1. My first question is very fanboyish. I am a huge fan of Peter Theil and would love to know if any of you have had a chance to interact with him. I know he left the company long back, but does he ever visit the PayPal offices still?

  2. What's your favorite thing about working at PayPal?

  3. If I were to choose a payment solution today for my app, should I use PayPal or Braintree? How are the two products differents given that both are from the same team?

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Aw, these are great questions!

  1. I've also never interacted with Peter Theil, but Dan, our CEO, is a super great guy and he takes time out of his busy day to talk with recent college grad nobodies like me :)

  2. My favorite things: the culture and the innovation lab. The culture because you can work from home whenever you feel like it, take long lunches if you've had a rough day, or work in the lounge. As long as you get your stuff done on time and your code is up to snuff, you can do whatever you need to do to recharge and keep your mind sharp. The innovation lab is also amazing. It's all about out-of-the-box thinking and daring to dream bigger and crazier ideas... and it's full of nerds who are learning everything from cryptocurrencies to VR. And the lab really expands your mind and they host great hackathons and events.

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I always had a question when building a software. How do you bring reliability in projects which are very critical like money transaction or things like spacecrafts? There is no(or very less) room to make mistakes. So how do you at PayPal do fault tolerance and ensure that system is consistent no matter what happens.

Mission critical systems generally have more testing than others, and PayPal is no different. In addition, PayPal has built-in redundancy and fault-tolerance to prevent bad code, a bad machine, network connection, router, data center, etc. from harming the service we provide to our customers. We have many layers of testing and alerting, so that if something goes wrong, we know almost immediately. If something does make it past all those layers, we have a Site Reliability Engineering (SRE) team and bug tracking system to ensure any customer issue gets the highest attention possible.

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