Sharp Edges in Kotlin Coroutines Testing Tools

At Cash App, we’re starting to integrate Kotlin coroutines into our app architecture. My coworker Bill, who has taken interest and ownership in this migration, came to me the other...

Gradle dependency license validation

Six years ago we added a screen to the Android Cash App to display the open source libraries we use and their licenses. This screen had to be updated manually,...

Migrating from Burst to TestParameterInjector

Square’s Burst library burst onto the scene in 2014 stemming from general dissatisfaction with JUnit 4’s built-in parameterized runner. It enabled the use of enums to vary input to your...

Rx to Coroutines Concepts, Part 1

The reactive paradigm is powerful, but can also be obscure. Coroutines provide an alternative paradigm that is better in every way.

Great teams merge fast

One of the many things I was constantly amazed about during my first few weeks at Square/Cash App was seeing how fast this team shipped code. All members of the...

AssistedInject is dead, long live AssistedInject!

After ~5 years of existing and ~4 years as an open source project, our AssistedInject library has been deleted. Mourn not, however, for the same functionality is now available directly...

protoc-gen-grpc-gateway-ts - Clean, Idiomatic TypeScript for grpc-gateway

protoc-gen-grpc-gateway-ts is a TypeScript client generator for the grpc-gateway project. It generates idiomatic TypeScript clients that connect the web frontend and golang gRPC backend fronted by grpc-gateway.

Rolling Out Org-Wide Changes

Cash App has grown into a complex engineering organization. Our team of hundreds of engineers deploys dozens of services to AWS multiple times a day. Our teams span several time...

Investigating Crashes with Aardvark

Crashes can be one of the most straightforward types of issues to debug. There are many different categories of crashes that can happen on iOS - everything from bad memory...

Debugging UI Issues with AardvarkReveal

Reports of UI issues can be difficult to debug when the issue is not easily reproducible. Bug reports created through Aardvark include a screenshot of the app at the time...

Taking Bug Reporting Further

This week we released a new major update for Aardvark, our open source bug reporting framework for iOS. Aardvark makes it dead simple to create actionable bug reports from right...

Reverting Commits in Client Apps

When faced with a critical bug in a client app that’s already shipped to customers, one of the key first steps in the debugging process is finding the earliest commit...

Crouching Theme, Hidden DI

Have you ever thought of your theme as a dependency? This post explores different ways to provide a theme in your Android app.

Meet Barber💈: the best way to manage your Mustache

Cash App clients and services render thousands of English Mustache templates to send millions of personalized notifications, emails, text messages, and in-app UI daily to our customers.

Wire's Proto3 support is Out!

Starting in 3.3.0 Wire supports Proto3. What changes with Proto3? How does Wire make it comfortable to use? Let’s see.

What I Like About Views

Views are a big deal, fam. Here are some architectural guidelines we like to follow that help give Views the development focus they deserve.

Announcing Tempest 1.0

At Cash we love AWS DynamoDB. It has a nice API, is highly available, and is able to scale with our growing business.

Attacking Build Times With Sample Apps

With long build times come long iteration cycles. Sample apps can help with that.

Wire Support For Swift, Part 1

We’re excited to announce support for Swift in Wire. Wire already supports compiling your protocol buffer files into Java and Kotlin, and today Swift joins that family.

Request Affinity with Istio

Behind the scenes, much of Cash App consists of a set of distributed services running on a Kubernetes cluster in AWS. Our engineering team started moving services to Kubernetes over...