piitier — Polish PII Anonymisation (pii-5-v4)

Model description

piitier is a ModernBertForTokenClassification fine-tuned for Polish PII detection and anonymisation. It recognises 39 entity types encoded as 79 BIO tags (78 B-/I- tags + O).

Entity types

ADRES, CVV, DANE_ZDROWOTNE, DATA_URODZENIA, DOCHOD, EMAIL, GEO, IBAN, ICD10, IMIE, IP, KOD_POCZTOWY, KWOTA, LEK, LEKARZ, MIEJSCOWOSC, NAZWISKO, NIP, NPWZ, NR_DOKUMENTACJI, NR_DOWODU, NR_KARTY, NR_KW, NR_PASZPORTU, NR_POLISY, NR_PRAWA_JAZDY, NR_RACHUNKU, NR_REJESTRACYJNY, NR_SZKODY, NR_UMOWY, OSOBA, PESEL, PLACOWKA, PLEC, REGON, ROZPOZNANIE, TELEFON, VIN, WIEK

Lineage

Source: training/configs/pii-5-v3.yaml, training/configs/pii-5-v4a.yaml, training/configs/pii-5-v4.yaml.

Weights checksum

SHA-256 of model.safetensors (shipped): 94d43a6effabd3c3b1500d8f20f9d136aa77b39f2f4fb01fcf51dedd062fc94c

Source: eval/reports/pii-5-v4/2026-10-27-ner-benchv1-dev.md.

The intermediate pii-5-v4a checkpoint is local-only and not distributed; its model.safetensors was not available at release time (no sha256 recorded).

Formats

• safetensors (FP32): primary.
• FP32 ONNX (onnx/model.onnx + onnx/model.onnx.data): strict F1 0.9832, recall 0.9868 on data/synthetic/v0.3/dev.jsonl (2 363 documents) at threshold 0.78.
• INT8 ONNX (model_int8.onnx, dynamic quantisation, 310 MB): strict F1 0.9745, recall 0.9814 on the same split. Recall delta against FP32 is 0.0054, inside the 0.01 tolerance, so the export gate passed for this checkpoint. The earlier pii-5-v3 INT8 export failed the same gate (delta 0.018). Source: training/out/pii-5-v4/export_report.json, copied to this repository as export_report.json.

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Intended use and out-of-scope

In scope: detection and masking of personal data in Polish-language insurance, banking, and medical documents, for GDPR-compliance workflows.

Out of scope:

• Languages other than Polish.
• Pseudonymisation (replacement with consistent surrogates) — the model masks only.
• Coreference numbering (same entity across a document gets the same mask token) — not implemented; all spans are numbered independently.
• Quasi-identifiers (combinations of non-PII attributes that identify a person together).
• Non-textual PII (images, scanned PDFs without OCR).
• Fully autonomous anonymisation pipelines without human review.

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How to use

With piitier (recommended)

The piitier package adds a rule layer (checksum-valid identifiers: PESEL, IBAN, NIP, NPWZ, NR_KARTY, …) on top of the NER output, a risk-weighted fusion strategy, and a span renderer. Rules win over the NER model on any overlapping identifier span.

CLI:

piitier mask file.txt --model emgiezet/piitier --threshold 0.78

Python API:

from piitier import Anonymizer

anon = Anonymizer(model="emgiezet/piitier", threshold=0.78)
result = anon.mask("Jan Kowalski, PESEL 44051401359, zam. Warszawa")
print(result.text)

With plain transformers

Note: using transformers directly bypasses the rule layer and renderer. The rule layer catches checksum-valid identifiers that NER may miss or mis-label. For production anonymisation use the piitier API above.

from transformers import AutoTokenizer, AutoModelForTokenClassification, pipeline

model_id = "emgiezet/piitier"
tokenizer = AutoTokenizer.from_pretrained(model_id)
model = AutoModelForTokenClassification.from_pretrained(model_id)

ner = pipeline("ner", model=model, tokenizer=tokenizer, aggregation_strategy="simple")
spans = ner("Jan Kowalski, PESEL 44051401359, zam. Warszawa")
# Filter by score >= 0.78 to match the calibrated threshold
spans = [s for s in spans if s["score"] >= 0.78]

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Evaluation

Synthetic calibration split

Risk-group recall on calibration (source: training/out/pii-5-v4/MODEL_CARD.md):

bench/v1/dev

6 hand-written documents, 40 gold spans. Source: eval/reports/pii-5-v4/2026-10-27-ner-benchv1-dev.md.

Evaluation independence caveat: bench/v1/dev was the safety gate for threshold selection — the threshold 0.78 was chosen in part because it yields 0/40 leaked values on this split (thresholds ≥ 0.98 leaked 8/40 values on the same split). No frozen test split exists yet. These numbers are not independent of the threshold choice and should not be treated as held-out test performance.

Per-label weak spots (strict, bench/v1/dev)

Note: IMIE/NAZWISKO FPs arise partly because training templates annotate full names both ways (IMIE + NAZWISKO separately vs. OSOBA); the bench uses OSOBA throughout. Source: FINDINGS.md (Data section).

Throughput

31.18 docs/s, P95 latency 0.1085 s (NVIDIA RTX 3080, single-process inference). Source: eval/reports/pii-5-v4/2026-10-27-ner-benchv1-dev.md.

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Training data and provenance

• Synthetic corpus (data/synthetic/v0.3 and extensions): CC BY 4.0. Generated from publicly distributed templates shipped in this repository.
• Layout-donor documents: some templates were derived from insurance documents owned by the author (Max Małecki), who also owns and releases these weights. Those documents carried fictitious identities; the derived templates keep only layout, every value is a {{LABEL}} placeholder, and they are not redistributed (gitignored). No third-party data licence applies to the weights. A clean clone of this repository cannot exactly reproduce the v0.3 corpus or the calibration split (see FINDINGS.md, "Rebuild the local calibration split" section).
• The calibration split (1 031 docs) was built with seed 900042 from 338 templates (218 policy, 81 table), with 25 zero-gold duplicate rows removed.

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Licence and attribution

Apache-2.0. Derived from bardsai/eu-pii-anonimization-multilang-v2 (Apache-2.0, bards.ai).

See NOTICE:

piitier — Copyright 2026 Max Małecki. Model checkpoints are fine-tuned from bardsai/eu-pii-anonimization-multilang-v2 (Apache-2.0, bards.ai) and are distributed separately, each with its own model card.

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Known limitations

• Split-name decoding: the token decoder can split a single word across two entity types (e.g. Wiśniew as NAZWISKO + ska as OSOBA). Source: FINDINGS.md.
• No coreference numbering: the same entity appearing multiple times in a document receives independent mask tokens; consistent pseudonymisation is not supported.
• No pseudonymise: replacement with consistent surrogates is out of scope for v0.1.0.
• Quasi-identifiers out of scope: combinations of non-PII attributes (age, postcode, occupation) that jointly identify a person are not detected.
• Polish only: the base model is multilingual but this fine-tune was trained and evaluated on Polish text only.
• Small bench: bench/v1/dev contains 6 documents and 40 spans; per-label numbers are not statistically stable.
• IMIE/NAZWISKO annotation mismatch: training templates use IMIE + NAZWISKO for ~23 occurrences across 16 templates; bench/v1 uses OSOBA. Unifying templates requires a retrain. Source: FINDINGS.md.
• Payment-card false positives: the rule layer can match Luhn-valid 16-digit runs inside decimals or lock-file hashes. Source: FINDINGS.md.

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This is not a certificate of anonymisation.