Microsoft Presidio vs Llama Guard

Presidio is Microsoft's open-source PII detection and anonymisation toolkit, and it solves the guardrail problem most teams discover last: personal data flowing into prompts, and from there into a provider's logs and possibly their training data. It detects a wide range of entity types across text and images, supports custom recognisers for your own identifier formats, and offers redaction, masking and reversible pseudonymisation. MIT licensed, and it runs entirely locally — which is the only sane place to do this work.

Llama Guard is Meta's safety-classification model family, fine-tuned to classify prompts and responses against a configurable taxonomy — and unusually, the taxonomy is a parameter you can edit rather than a fixed list, so your categories can be your own. As a purpose-trained model it outperforms rule-based scanners on nuanced content. The caveat we will not bury: it ships under Meta's Llama Community License, not an OSI-approved open-source licence. It is free for most use but carries acceptable-use terms and a scale threshold, so it is not open source in the sense the rest of this list is.