After six years building full-stack applications and another six years in platform engineering, DevOps, and SRE, I thought I knew cloud development. When I became a Google Cloud Developer Expert this year focusing on application modernization, I figured the Professional Cloud Developer certification would be straightforward validation of what I already knew.

I was wrong—and that’s exactly why the certification was worth pursuing.

Why Certification Mattered (Even as a Developer Expert)

Becoming a Google Cloud Developer Expert opened doors to working with enterprises on application modernization. But it also revealed something uncomfortable: my expertise was deep in specific areas while other Google Cloud services remained theoretical knowledge at best.

The certification wasn’t about proving myself to others—it was about identifying and filling the gaps in my own understanding. As experienced developers, we often assume our transferable knowledge covers everything. The exam forces you to confront what you actually don’t know.

The Reality Check: Even Experienced Developers Have Gaps

Despite my extensive background, studying revealed blind spots I hadn’t expected. The most glaring was Apigee. I’d built APIs, worked with API gateways, and understood the patterns conceptually. But I’d never actually used Apigee in production environments.

This highlighted a broader issue for experienced developers approaching Google Cloud: we assume familiarity with concepts equals proficiency with Google’s specific implementations. Cloud SQL isn’t just “managed databases.” Cloud Functions isn’t just “serverless compute.” Each service has unique characteristics, limitations, and integration patterns that matter in real implementations.

My Study Approach: Connecting Theory to Practice

Rather than memorizing service features, I related every practice question back to real-world scenarios I’d encountered. When studying Cloud Functions, I thought about the serverless migrations I’d led. For Cloud SQL, I recalled database scaling challenges from past projects.

The Google Cloud Developer Learning Path became my primary resource because of its comprehensive, organized structure. It didn’t just explain what services do—it showed how they connect to solve actual problems. For an experienced developer, this contextual approach worked far better than feature-focused study guides.

The key was treating each practice question as a mini case study rather than a memorization exercise.

Case Study: Learning Apigee From Zero

Apigee represented my biggest knowledge gap. Understanding API management conceptually wasn’t enough—I needed hands-on experience with Google’s specific implementation.

I built a personal project that required API versioning, rate limiting, and analytics. Working through Apigee’s console, policies, and developer portal gave me the practical context that no documentation could provide. The exam questions suddenly made sense because I’d wrestled with the actual interface and configuration options.

This reinforced an important lesson: experienced developers can’t skip the hands-on experimentation. Our background accelerates learning, but it doesn’t replace the need to actually use the tools.

What This Means for Experienced Developers New to GCP

Three months of focused study taught me that Google Cloud proficiency requires more than mapping existing knowledge to new service names. Each Google Cloud service has evolved to solve specific problems in particular ways. Understanding those design decisions—and their practical implications—is what separates surface-level knowledge from real expertise.

The certification process revealed gaps I didn’t know I had and gave me confidence in areas where I’d previously relied on theoretical understanding. For experienced developers considering Google Cloud, the exam isn’t just validation—it’s education.

And yes, make sure your cat’s toys are turned off before you start the exam.