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Insights on building software, scaling teams, and working with AI — from the people who do it every day.

Engineering
6 min read

Czech Bluetooth Tech Among TIME's Best Inventions 2025

When TIME Magazine selected Evenflo's smart car seat as one of its Best Inventions of 2025, it was recognition for Czech developers. We built the IoT app powering it.

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Node.js Event Loop: Practical Overview and Best Practices
Engineering

Node.js Event Loop: Practical Overview and Best Practices

A practical deep-dive into the Node.js Event Loop -covering macrotasks, microtasks, Worker Threads, starvation, and real code challenges to test your understanding.

6 min read
Engineering

Why code quality pays off: How Biome helped us build faster, cleaner TypeScript projects

Code quality is not the KPI clients usually look for, but at Cookielab we believe it's a must. We share how we use Biome with a strict custom configuration to enforce safety, performance, and developer experience across all our TypeScript projects.

4 min read
One of TIME's Best Inventions of 2025 runs on Czech software
Company

One of TIME's Best Inventions of 2025 runs on Czech software

TIME magazine included Evenflo's SensorySoothe in its Best Inventions of 2025 list -and the app behind it was built by us.

3 min read
Engineering

Is your Android app DDoSing your backend?

If your Android app calls your backend in Application.onCreate and supports Firebase push notifications, you might unknowingly be triggering thousands of API calls every time a notification is delivered -even when no user is present.

4 min read
SlackTiquette: how to communicate on Slack effectively
Company

SlackTiquette: how to communicate on Slack effectively

8 practical tips we use at Cookielab to keep Slack clear, fast, and stress-free -feel free to steal them.

4 min read
Engineering

iOS Cookie Crumbs: May the force (unwrap) not be with you

Force unwrapping optionals in Swift is a two-sided sword. Here's when it's fine -and when it will crash your app.

3 min read
Package Managers Comparison: Yarn, NPM, PNPM
Engineering

Package Managers Comparison: Yarn, NPM, PNPM

A detailed look at the three most popular JavaScript package managers. We break down hoisting, Plug'n'Play, symlinks, and CorePack -so you can make an informed choice for your next project.

5 min read
Engineering

Subtleties of Software Testing (Plus a Practical Example)

Frontend developer Ondřej Hajný shares hard-won lessons from testing a Kiwi.com application with Jest and Testing Library -covering side-effect module mocking, partial mocks, async gotchas, and useful tooling.

8 min read
European Coffee Trip releases mobile app for coffee lovers
Company

European Coffee Trip releases mobile app for coffee lovers

The leading European specialty coffee guide launches its long-awaited iOS app -built by Cookielab.

3 min read
Tackling recursion (not just) in TypeScript
Engineering

Tackling recursion (not just) in TypeScript

Deep-diving into stack overflow risks with recursive functions in TypeScript and how trampolining solves them elegantly.

5 min read
Engineering

How to write your own JSON parser using functional TypeScript & fp-ts -part I

Building a fully functional JSON parser from scratch using fp-ts: defining parser types, composing parsers and combining them into sequences.

6 min read
Engineering

How to read config values from env using io-ts

A short guide to reading environment variables in a type-safe, functional way using io-ts -with human-readable error reporting.

3 min read
Engineering

Open Source @ Cookielab

Why we open-source our internal tools, how we decide what to share, and the projects we're most proud of.

3 min read
Best Practices aka How not to be the worst developer
Engineering

Best Practices aka How not to be the worst developer

A practical checklist of habits every developer should adopt -from writing tests and doing proper code reviews to using linters and avoiding the any type.

6 min read
Authentication: The Technological-Product View
Engineering

Authentication: The Technological-Product View

Before picking an auth library, you need to answer dozens of product questions. This article walks through all of them.

7 min read

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