From Manual to Magic: How I Used Keploy to Test APIs on YouTube and Amazon

Diptesh Bal — Fri, 27 Jun 2025 17:50:33 +0000

APIs are the backbone of modern web apps, but testing them? That’s where many devs, including me, used to burn time.

Recently, I discovered Keploy, an AI-powered API testing tool, and decided to try it out on two API-heavy websites I use often: YouTube and Amazon. Spoiler: I went from zero test coverage to 100% functional coverage of real-world user flows — in minutes.

Here’s how it went, what I learned, and why I think AI might just be the future of API testing.

Why YouTube and Amazon?

Both of these websites are API monsters:

YouTube: Every search, video load, comment, and recommendation is driven by background API calls.
Amazon: From product listings to price and shipping info, nearly everything on a product page is dynamically fetched.

Perfect targets to stress test an API testing tool.

Getting Started with Keploy

Setting up was smooth:

Installed the Keploy API Testing Chrome Extension.
Browsed YouTube and Amazon like a normal user — searched, clicked, scrolled.
Keploy silently recorded the API calls in real-time.

Within seconds, I had a test suite auto-generated from real user interactions.

Testing YouTube

Keploy captured calls like:

GET /search (video search)
GET /watch (load video details)
GET /comments (load comments)

I replayed these through Keploy. It verified responses and flagged mismatches, especially for dynamic values like timestamps or suggestion IDs.

✨ What stood out:

Keploy caught minor changes I wouldn’t notice manually.
No Postman. No scripting. Just record and replay.

Testing Amazon

Amazon was even more API-rich. Keploy captured:

Product list API (search)
Product detail API (price, availability, ratings)
Shipping estimate API

Amazon’s APIs return a lot of dynamic data (e.g., offer IDs, tracking info), which occasionally caused false negatives on replays. Still, a few tweaks to filters and I was golden.

Manual vs. Keploy: A Quick Comparison

Task	Manual Testing	Keploy + AI
Capture API traffic	DevTools/Charles, manual	Automatic
Write test scripts	Manually, one by one	Auto-generated
Handle dynamic values	Tedious	Smart comparison engine
Replay tests	Postman/cURL	One-click in dashboard
Time spent	Hours	~10 minutes

Challenges I Faced

Dynamic tokens & sessions: Amazon's APIs return session-bound data. Replays required small tweaks or tokens.
Authentication: Some calls are gated. Keploy works best during real authenticated sessions.
Noise filtering: Sites like Amazon fire tons of tracking APIs — it helps to focus only on the key business logic calls.

Why I’m Excited About AI Testing

Keploy flipped the API testing game for me. Here's what stood out:

✅ Zero test writing — everything came from real user sessions.

✅ Quick feedback loops — replaying tests after changes is painless.

✅ High confidence — I actually trust my coverage now.

As devs, we’re always chasing better velocity without compromising quality. AI tools like Keploy seem to be closing that gap — fast.

Final Thoughts

If you’re a dev or tester who’s still manually writing API tests or maintaining brittle test suites — give Keploy a shot.

✅ Record real traffic

✅ Auto-generate tests

✅ Replay and verify responses

It's not magic. But it kind of feels like it.

Your turn: Have you used AI-based tools for API testing?

Drop your thoughts in the comments — I’d love to compare notes.

🛠️ Tools Mentioned

🔗 Keploy Chrome Extension
🧠 Keploy GitHub

DEV Community: Diptesh Bal