GPT-5.5 vs Claude Opus 4.7: I Made Both Build an App - Here's What Happened

Snyk

May 4, 2026

GPT-5.5 vs Claude Opus 4.7 - two flagship AI models dropped one week apart, and both claim to be the best at agentic coding. We put that to the test by giving each model the exact same prompt: build a production-ready, secure note-taking application from scratch.

But we didn't stop at reviewing the code. We actually tried to break it by running real security tests against each app to see whether AI-generated code can be trusted with user data. The results were not what we expected.

In this video:

The exact prompt we gave both models (no hand-holding)
Side-by-side breakdown of what each model built
Security testing each application - what we found
Which model writes safer, more production-ready code
Final verdict: GPT-5.5 or Claude Opus 4.7 for real dev work?

For context: Claude Opus 4.7 leads SWE-Bench Pro for real-world code
resolution, while GPT-5.5 leads the CyberGym security benchmark. On paper,
GPT-5.5 should write more secure code. But does that show up when you
actually test the app it builds?

Watch to find out.

Use Snyk for free to find and fix security issues in your applications today! https://snyk.co/ugLYn

✍️ Resources ✍️

Claude Opus 4.7: https://www.anthropic.com/news/claude-opus-4-7
GPT-5.5: https://openai.com/index/introducing-gpt-5-5/
Snyk IDE Plugins: https://snyk.io/platform/ide-plugins/

⏲️ Chapters ⏲️

00:00 Claude Opus 4.7 vs. GPT-5.5

00:46 The Prompt

01:06 The Results Comparison

02:39 Opus 4.7's Secure Notetaking App

03:47 Opus 4.7 App Security Test

07:35 GTP-5.5's Secure Notetaking App

08:51 GTP-5.5's App Security

10:45 Who's The Winner?

⚒️ About Snyk ⚒️

Snyk helps you find and fix vulnerabilities in your code, open-source dependencies, containers, infrastructure-as-code, software pipelines, IDEs, and more! Move fast, stay secure.

Learn more about Snyk: https://snyk.co/ugLYl

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