Claude 4.7 regressions are real. ClaudeVersionLock lets you test your prompts against multiple Claude versions, see exactly which one passes your tests, and pin your API calls to the winner.
Claude 4.7 introduced real regressions. Developers across Reddit and Discord are reporting the same issues.
"Claude 4.7 completely broke my code generation pipeline. 4.6 was perfect."
"I'm at a loss. Same prompts, same system instructions, totally different output quality."
"Had to roll back my entire integration because 4.7 keeps hallucinating function signatures."
Test once. Pin forever. Never get surprised by a model update again.
Run your exact prompts against claude-3-5-sonnet (4.6) and claude-sonnet-4-5 (4.7) simultaneously. See which version actually passes your test cases.
Get the exact API model string to hardcode in your integration. No more silent upgrades breaking your production pipeline.
Define your own pass/fail criteria. Check for exact strings, regex patterns, or just eyeball the output — you decide what "correct" means.
See aggregate pass rates across all your test cases. Instantly know which model version is the winner for your specific use case.
Tests run in parallel. No waiting around. Get your comparison in seconds, not minutes.
We never store your prompts or API keys. Everything runs in your browser session. Your IP, your data.
Enter your Anthropic API key. It stays in your browser — we never see it.
Paste the prompt that's been breaking. Add what the correct output should contain. Add as many test cases as you need.
We call both model versions with your exact prompt and show you side-by-side results with pass/fail for each test.
Copy the exact model string for the version that works. Paste it into your code. Done.
3 free test runs. No credit card. No BS. Just answers about which Claude version works for your code.