Toptal Engineering Blog

As a good JavaScript developer, you strive to write clean, healthy, and maintainable code. While you solve interesting and unique challenges, you’ve likely found that you’re often writing code that looks similar to the code for an entirely different problem you’ve handled before. You may not know it, but you’ve used a design pattern.

Interacting with a real database during integration and end-to-end testing can pose distinct challenges. An effective workaround is to use an in-memory database that integrates seamlessly with your testing framework and provides APIs for manipulating state directly from your test code.

In this article, Toptal Software Engineer Mikhail Angelov demonstrates how to do just that—and how to write straightforward integration and end-to-end tests for Node.js and MongoDB applications without the need for complicated setup/teardown code.

Launch yourself into Ethereum smart contract development with the Truffle framework! In this tutorial, Toptal Freelance Ethereum Developer Radek Ostrowski shows you how to create a practical ĐApp in the Solidity language, complete with its own ERC20 token.

For a large codebase, managing database schema can become tedious, especially if you maintain multiple testing environments or customers that update the product at different paces. Sometimes, documenting the latest schema or database changes isn’t enough.

In this article, Toptal Database Engineer Ivan Pavlov introduces us to concepts that help manage database states.

Angular 5 is a new version of the Angular framework developed by Google. Angular 5 comes with improvements including optimized builds and faster compile times, but in this Angular 5 tutorial, we are going to build a notes app from scratch. If you’ve been waiting to learn Angular 5, this tutorial is for you.

Open-source, IoT, and Ethereum smart contracts work together with a new utility coin to make transportation more accessible and reduce vehicle waste. In this article, Toptal Freelance Ethereum Developer Michał Mikolajczyk explains the motivations and methodology behind his startup’s latest initiative.

Mixed-integer programming is one of the many ways you can automate and enhance your decision-making processes.

In this article, Toptal Freelance Software Engineer Shanglun Wang explores the power of operations research by walking through a hypothetical problem and shows how mixed-integer programming can be used to solve it.

While machine learning sounds highly technical, an introduction to the statistical methods involved quickly brings it within reach. In this article, Toptal Freelance Software Engineer Vladyslav Millier explores basic supervised machine learning algorithms and scikit-learn, using them to predict survival rates for Titanic passengers.

In this article, Toptal Freelance Software Engineer Piotr Gaczkowski explains how to make the most out of command line tools and lists some of the best tools out there.

Apache JMeter and REST Assured are two very popular Java-based tools for automated testing of REST API services.

In this article, Toptal Freelance Java Developer Nemanja Veskovic gives us an overview of the pros and cons of both of these tools and shows where they fit best in your existing REST API projects.

Non-Salesforce app developers may be overlooking a hidden gem in the AI world: Salesforce Einstein offers image recognition and text analysis for plain-vanilla apps and Salesforce apps alike. In this article, Toptal Freelance Salesforce Developer Fahad Munawar Khan shows how any developer can leverage Einstein Vision and Einstein Language.

Asynchronous programming used to be a challenge even for seasoned professionals, leading to aptly named phenomena like Callback Hell.

In this article, Toptal JavaScript Developer Demir Selmanovic explains how async functions took us out of purgatory and why you should be using them.

Fragment caching in Rails provides an easy yet a powerful way of improving your application’s performance. However, some real-world scenarios do not work quite well with how the Rails cache behaves by default.

In this article, Toptal Ruby on Rails Developer Orban Botond shows how you can implement a small DSL to optimize how the cache for related entities is invalidated to improve template rendering performance.

Designing systems integration architecture can be a difficult task. And it gets worse if you’re designing for software at scale. An enterprise service bus can be one way of working around the challenges. But this is definitely not the simplest of solutions.

In this article, Toptal Freelance Software Engineer Anton Goncharov gives us a detailed overview of the challenges of systems integration and a guide to addressing those challenges with Apache Camel.

In this article, Toptal Freelance Software Engineer Neven Pičuljan introduces you to the intricacies of deep learning in hedge funds and finance in general.

In a recent project, there were several programmatic tasks I needed to repeat periodically. One task in particular involved updating user-level permissions based on evidence of membership level purchase or subscription.

Instead of going into the admin panel and manually deleting hundreds (maybe thousands) of subscriptions, I opted to reach for one of my favorite WordPress tools: WP-CLI, which fixed the problem in a few keystrokes.