Andrzej Karaś

Senior Software Engineer

SaaS products · Backend systems · Software architecture · Browser extensions · Testing & reliability

Notes and lessons from building, testing and running software in production.

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How 150k emails a day exhausted a shared quota for all our apps, and why splitting quotas per service lets your system fail gradually.

Manifest V3 removed blocking webRequest, but enterprise and self-hosted extensions can still use it. Here's how, and the catches.

A simple trick to catch what your Manifest V3 service worker does right after start: delay the code so you can open DevTools in time.

Posted on Oct 6, 2026 · 5 min read

We tested a new WebSocket relay by changing the default settings, and customers behind strict firewalls lost live sessions. What I learned from it.

Posted on Jan 22, 2024 · 3 min read

What I learned when a code-review comment of mine was taken as an order: explain the why, and treat review comments as discussion.

Posted on Apr 3, 2023 · 2 min read

Before presenting a design, list the questions your CTO, teammates and other teams will ask, and answer them first.

Posted on Mar 30, 2023 · 3 min read

Stuck on a bug or feature? Timebox it, take breaks, rubber-duck it or ask a teammate, instead of sitting at your desk until it's solved.

Posted on Mar 27, 2023 · 5 min read

Implemented, reviewed, tested, deployed: the levels of "done" I've seen, and why your team needs a shared definition of done.