I shipped a Flutter app to production last year with an LLM chatbot baked in. Two weeks later a user pasted their Aadhaar number into the chat, the model echoed it back, and I spent a weekend writing a PII scrubber by hand. That scrubber grew into ai_guardrails .

Python has NeMo Guardrails, Guardrails AI, LLM Guard. Dart had nothing. If you're building AI features in Flutter or server-side Dart, you've been on your own for input/output safety. This package closes that gap: 35 scanners, 893 tests, zero runtime dependencies, runs anywhere Dart runs.

What it actually does

ai_guardrails sits between your user's text and your LLM call. Input scanners run first: they can redact PII, block prompt injection attempts, catch leaked secrets. Then your LLM runs. Output scanners validate what comes back: JSON schema conformance, hallucination flags, toxicity scores, reading level checks.…