Presidio / custom regex vs NoeticGuard for prompt scrubbing

Microsoft Presidio and custom regex are common starting points for “scrub the prompt.” They can work — with caveats for LLM products.

• Presidio — strong NLP-oriented PII detection, typically a service you operate. You still need vault/session design for reversible tokens and a product path for browser ChatGPT (Presidio alone is not a Chrome extension).
• Custom regex — fast to prototype, brittle across locales (IBAN, TR TCKN, Luhn cards), and usually non-deterministic placeholders that break agent traces.
• NoeticGuard — local-first engine shared by SDK, CLI, and Browser Shield; deterministic [EMAIL_n]-style tokens; API for GET /v1/config + POST /v1/telemetry only (ng_pub_ / ng_secret_). SDK and CLI packages are not on the public npm registry yet.

Choose Presidio when you already run a central NLP PII stack and only need backend scrubbing. Choose NoeticGuard when you want one engine across three surfaces (employees in browser LLMs, repo CLI measure, product SDK) without uploading raw prompts to a masking cloud.

Full feature matrix: Presidio vs NoeticGuard.