FenceLint – Testing framework for AI applications

Summary: FenceLint is a free, open-source testing framework for AI applications that detects security vulnerabilities, monitors API costs, and catches breaking changes before production. It supports OpenAI, Anthropic, and Gemini models, providing detailed test results including pass/fail status, security scores, and cost breakdowns.

What it does

FenceLint enables developers to write and run tests that verify AI responses, scan for 20 known attack patterns, and track API usage costs. It integrates via npm and auto-detects AI models from their names.

Who it's for

It is designed for AI developers who need to ensure application reliability, security, and cost control before deployment.

Why it matters

FenceLint addresses silent AI failures, security risks from prompt injections, and unexpected API expenses by providing pre-production testing and monitoring.