OpenAI has released its Privacy Filter as an open-weight model under an Apache 2.0 license, letting anyone download and run it locally. The company claims it scores 97.43 percent on its own benchmark — a common machine learning accuracy metric where 100 percent means perfect detection. The best existing open-source tool, Microsoft Presidio, scores 0.14 on the same type of test. No independent researcher has published results running Privacy Filter against the academic benchmark that produced the 0.14 figure, and OpenAI's own 97.43 percent has not been verified by anyone outside the company.
The model is a 1.5-billion-parameter language model with 50 million active parameters per token, using a sparse mixture-of-experts architecture. It processes up to 128,000 tokens in a single pass and can be fine-tuned on domain-specific data, improving from a 54 percent F1 baseline to 96 percent with even a small custom dataset. For a hospital processing clinical notes, a law firm handling discovery documents, or a fintech company running automated compliance checks, that combination of accuracy and local deployment is the practical pitch.
OpenAI evaluated the model on PII-Masking-300k, a widely used training dataset for PII detection tools, after correcting annotation errors it identified during its own review. The corrected score was 97.43 percent, up from 96 percent before the fixes. On PIIBench, a newer academic benchmark published five days earlier by researchers at Johns Hopkins, UC Berkeley, and elsewhere, every system the benchmark authors tested scored below 0.14 F1, with Presidio at 0.1385. Those numbers are not directly comparable — PIIBench is harder and more diverse — but a gap between 0.14 and 97 percent is large enough to be worth naming.
The Apache 2.0 license means the community can run its own evaluations. Nobody has yet. Whether the first independent results confirm the 97 percent figure or complicate it will determine whether Presidio and similar tools become legacy infrastructure or whether OpenAI's announcement was a positioning move that landed before the data was in.
Microsoft did not respond to a request for comment by publication time.