Both can self-host, so start with the license
The first thing to get straight is that this is not a self-hosted-versus-cloud comparison. Private AI offers a container you can run in your own infrastructure, just as Philter does, so for teams that deploy the container, sensitive data can stay inside the perimeter in both cases. That is a point in Private AI’s favor relative to pure-SaaS competitors, and worth saying plainly.
The real fork is the license and what it buys you. Philter is open source under the Apache 2.0 license, and every detection rule, model, and policy behavior is in source you can read on GitHub. Private AI is a commercial, closed-source product: you can run the container, but you cannot read the logic that decided a given token was or was not PII. For a buyer who has to defend a redaction decision to an auditor or regulator, that difference is the whole game, which is the argument we make in Show me the code path.
Where Private AI is genuinely strong
It is worth being honest about Private AI’s strengths, because they are real and they matter for some workloads:
- Multi-modal redaction. Private AI redacts not just text but PDFs, images, and audio through one API. If your pipeline needs to scrub identifiers out of scanned documents or call recordings out of the box, that breadth is a genuine convenience. Philter focuses on text and PDF; for audio you would pair it with a speech-to-text step (see redacting audio transcriptions).
- Broad language coverage. Private AI ships wide multilingual support without configuration. Philter covers general and healthcare English strongly and extends to other languages through swappable PhEye lenses, which is flexible but is not the same as dozens of languages enabled by default.
If your primary need is “one vendor API that handles many file types in many languages,” Private AI’s breadth is a legitimate reason to choose it.
Where Philter pulls ahead
Philter’s advantages cluster around depth, auditability, and the surrounding toolkit:
- Policy depth. Philter exposes a full policy engine: dictionaries, custom regex, identifier patterns, conditional rules (redact a ZIP code only when its population is below a threshold, redact an age only when over a value), per-entity replacement strategies, and format-preserving encryption. That control is the difference between “redact the built-in entity types” and “encode exactly the privacy behavior your downstream systems need.”
- The toolkit, not just an API. Redaction is one job. Philter sits next to Phinder for discovery, Phield for PII drift monitoring, Philter Scope for measuring redaction quality, the Philter AI Proxy for guarding LLM traffic, and Philter Diffuse for differentially private analytics. Private AI is focused on the detection-and-redaction step.
- Embeddable. Beyond the API, the Phileas library lets you compile redaction directly into a JVM, Python, or Go application with no service to call.
- Auditable accuracy. You do not have to take an accuracy claim on faith. You can measure precision and recall against your own gold-standard set with Philter Scope and put the number in the audit file.
Pricing posture
Private AI uses commercial, usage-based pricing negotiated with sales; the closed-source license is part of what you are paying for. Philter is free and open source, with paid, predictable per-instance-hour deployment on the AWS, GCP, and Azure marketplaces ($0.49/hr) and optional commercial support. For high-volume workloads, per-instance pricing flattens out in a way usage-based pricing does not, and there is no per-call license cost on the open source engine itself.
What to do next
If broad multilingual and multi-modal coverage from a single commercial vendor is the priority, Private AI is a reasonable choice. If open source and auditability are requirements, if you want policy depth and format-preserving encryption, or if you want the surrounding discovery, monitoring, benchmarking, and LLM-proxy tooling rather than a redaction API alone, start the evaluation on Philter. The migration guide covers how the concepts map if you are moving off Private AI.