FAQ¶
Is it really necessary to anonymize PII before calling an LLM?
Yes, and this holds regardless of piighost. The stakes (exfiltration to providers, legal requisition, training on conversations, GDPR compliance, data leaks) are covered in Why anonymize?. The page is library-agnostic: it explains why the problem exists before justifying a solution like piighost.
Which languages are supported?
It depends entirely on the detector you plug in. The pipeline itself is language-agnostic. With Gliner2Detector and a multilingual GLiNER2 model, you get about 100 languages out of the box. With a spaCy detector, whatever spaCy supports. With RegexDetector, language is irrelevant. See Extending PIIGhost for the detector catalogue.
Which entities are detected out of the box?
None. piighost does not ship its own NER model, this is a deliberate design choice. You bring the detector. Use ExactMatchDetector for fixed dictionaries, RegexDetector with piighost.detector.patterns (FR_IBAN, FR_NIR, EU_VAT…), Gliner2Detector for open NER (PERSON, LOCATION, ORGANIZATION, EMAIL, any label you ask for), or compose them via CompositeDetector.
What latency does the pipeline add?
The pipeline itself is on the millisecond scale (regex and lookups). The real cost comes from the detector. GLiNER2 on CPU for a 200-token message is typically 50 to 200 ms. An LLM used as a detector, several hundred milliseconds. The pipeline caches detections by text hash via aiocache, so repeated content is free. Measuring on your actual workload remains recommended before sizing production.
Does piighost work 100% offline?
Yes. With a local detector (Gliner2Detector, spaCy detector, RegexDetector, ExactMatchDetector), no data leaves your process. The middleware only forwards already-anonymized text to the LLM. This is the main reason teams adopt piighost, keeping a hosted LLM under GDPR constraints without exfiltrating raw PII. See Why anonymize? for the legal context.
Do my placeholders have to look like <<PERSON:1>>?
No. The format is driven by AnyPlaceholderFactory. By default LabelCounterPlaceholderFactory produces <<LABEL:N>>, but LabelHashPlaceholderFactory yields <<LABEL:hash>>, LabelPlaceholderFactory produces <<LABEL>> without a counter, and you can write your own factory. See Placeholder factories.
Does the LLM see raw PII when it calls a tool?
It depends on tool_strategy. With the default (FULL), no. The middleware deanonymizes arguments right before the tool executes, then re-anonymizes the tool response before it flows back to the LLM. The tool sees real values; the LLM only sees placeholders. The INBOUND_ONLY and PASSTHROUGH modes change this behaviour, see the next question and Tool-call strategies. Full diagram in Architecture.
How do I control what a tool sees: placeholder or real value?
The tool_strategy parameter of PIIAnonymizationMiddleware exposes three modes (FULL, INBOUND_ONLY, PASSTHROUGH) via the ToolCallStrategy enum. The right choice depends on whether the tool may emit new PII and how strict the privacy boundary needs to be. See Tool-call strategies for the trade-offs and the decision tree, and Placeholder factories for the factory constraint that forces PreservesIdentity in every mode but PASSTHROUGH.
What happens if the LLM hallucinates a PII that was not in the input?
It is not anonymized by piighost: entity linking works on detections coming from the input, not on invented values. To cover that case, add a post-response detection pass at the application layer. See Limitations.
Is the cache shared across threads or conversations?
No. The aiocache cache is scoped by thread_id. Two parallel conversations never see each other's placeholders, preventing cross-user leaks. The thread_id is extracted automatically from the LangGraph config.
Can I use piighost without LangChain?
Yes. AnonymizationPipeline and ThreadAnonymizationPipeline are usable standalone, without the middleware. See Basic usage.
Does piighost encrypt cached data?
No. The cache stores the placeholder → value mapping in memory (or in the aiocache backend you configured). See Security for the full list of things out of scope.