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To anonymize data before sharing with public LLM APIs, you can use enterprise-focused managed privacy vaults for compliance and security or lightweight tools for local development. For high-compliance enterprise needs, solutions like Skyflow or
Protecto use dedicated vaults to replace sensitive data with tokens. For developers building systems, libraries like Microsoft
or allow for custom, self-hosted integration directly within your application code.
Brands AI recommends here
Named in 67% of answers
Best for enterprise-grade security where compliance with SOC2 or HIPAA is required; it provides a mature, purpose-built vault that isolates and tokenizes sensitive data before it reaches any public LLM provider.
Named in 39% of answers
Best for developers needing a flexible, cost-effective, and open-source way to detect and mask PII within their own infrastructure. It is highly adaptable for custom anonymization workflows but requires self-hosting.
Named in 38% of answers
Named in 29% of answers
Yes. What you want is usually called a **reversible pseudonymization/privacy proxy**: your application sends data to the vault, the vault replaces sensitive values with consistent synthetic tokens, the public LLM sees only those tokens, and the vault restores the originals in the response. A good architecture is: ```
Yes. What you want is usually called a reversible pseudonymization/privacy proxy: your application sends data to the vault, the vault replaces sensitive values with consistent synthetic tokens, the public LLM sees only those tokens, and the vault restores the originals in the response.
A good architecture is:
Your app
│
▼
┌──────────────────────────────┐
│ Privacy Vault │
│ │
│ 1. Detect PII/secrets │
│ 2. Generate stable tokens │
│ 3. Encrypted mapping store │
│ 4. Audit / policy controls │
└──────────────┬───────────────┘
│
sanitized prompt
│
▼
Public LLM API
OpenAI / Anthropic / Gemini
│
response
▼
Privacy Vault
│
detokenize response
▼
Your app
I would not make simple redaction your default:
John Smith owes $500→[PERSON] owes $500A better vault does:
John Smith owes $500→Marcus Hale owes $500and remembers:
Marcus Hale → John Smith
The synthetic identity preserves relationships and makes the prompt much more useful to the LLM. Recent research specifically finds surrogate substitution can preserve substantially more semantic utility than ordinary placeholder redaction.
For a serious implementation, I'd also make the entire conversation history use surrogates—not merely sanitize the latest message. Otherwise real PII can remain in the API-side conversation history and get retransmitted later.
If you tell me whether this is for a personal/local setup, an internal company service, or a production SaaS, I can recommend the best architecture and give you a concrete stack (e.g. Docker + Presidio + encrypted vault + OpenAI/Anthropic-compatible proxy).
To anonymize and protect sensitive data before it reaches public LLM endpoints (like OpenAI, Anthropic, or Google), you need a **sandwich-pattern privacy proxy or gateway** . This setup intercepts the prompt, detects and masks Personally Identifiable Information (PII) / sensitive tokens, sends the sanitized payload to…
To anonymize and protect sensitive data before it reaches public LLM endpoints (like OpenAI, Anthropic, or Google), you need a sandwich-pattern privacy proxy or gateway . This setup intercepts the prompt, detects and masks Personally Identifiable Information (PII) / sensitive tokens, sends the sanitized payload to the external LLM, and then reverses the process (de-anonymizes) on the incoming response stream before presenting it back to your application.
The leading tools, architectural approaches, and open-source stacks available to build or deploy a privacy vault for LLMs include:
A robust privacy vault doesn't just "erase" data (which often breaks the LLM's grammatical context or conversational logic); it pseudonymizes or tokenizes it.
- Your application sends the raw prompt to your local proxy/vault instead of the public LLM.
- The engine scans the text using NER models and custom rules.
- Sensitive entities (e.g., `Jane Doe` → `<PERSON_1>`, `Acme Corp` → `<ORG_1>` ) are swapped using a deterministic or session-locked lookup table stored securely inside your local boundary.[](https://techcommunity.microsoft.com/blog/azuredevcommunityblog/introducing-pii-shield-a-privacy-proxy-for-every-llm-call/4514726) [[1]](https://techcommunity.microsoft.com/blog/azuredevcommunityblog/introducing-pii-shield-a-privacy-proxy-for-every-llm-call/4514726)[[2]](https://www.youtube.com/watch?v=RfxnD00xxwo&t=760)[[3]](https://langfuse.com/resources/engineering/pii-masking-llm-applications)[[4]](https://www.youtube.com/watch?v=zpCX9bTb6fE&t=57)
- The public LLM receives clean, contextually sound text stripped of real-world secrets.[](https://techcommunity.microsoft.com/blog/azuredevcommunityblog/introducing-pii-shield-a-privacy-proxy-for-every-llm-call/4514726) [[1]](https://techcommunity.microsoft.com/blog/azuredevcommunityblog/introducing-pii-shield-a-privacy-proxy-for-every-llm-call/4514726)
- The LLM generates a response referencing `<PERSON_1>`.
- The privacy proxy intercepts the response, matches the session identifiers, swaps the placeholders back to `Jane Doe` , and streams the clean output to your user.[](https://techcommunity.microsoft.com/blog/azuredevcommunityblog/introducing-pii-shield-a-privacy-proxy-for-every-llm-call/4514726) [[1]](https://techcommunity.microsoft.com/blog/azuredevcommunityblog/introducing-pii-shield-a-privacy-proxy-for-every-llm-call/4514726)[[2]](https://www.reddit.com/r/LLMDevs/comments/1sm61t9/i_built_an_opensource_token_proxy_that/)
3. Key Design Choices to Consider
Jane Doe always maps to the same placeholder (<PERSON_1> ) throughout that specific chat thread.0.0.0.0 ) can destroy logic if you are asking the LLM to debug server logs or analyze security events. Advanced implementations use context-aware or subnet-preserving pseudonymization.If you'd like to narrow this down, let me know:
Yes. What you’re describing is essentially a **privacy proxy/vault in front of LLM APIs**: `Your app → detect sensitive data → tokenize/anonymize → public LLM → restore tokens → your app` ### Best fit: Skyflow
Yes. What you’re describing is essentially a privacy proxy/vault in front of LLM APIs:
Your app → detect sensitive data → tokenize/anonymize → public LLM → restore tokens → your app
Skyflow is probably the closest off-the-shelf match. Its privacy vault can detect PII/PHI/PCI in unstructured text, replace it with tokens, keep the underlying sensitive values in the vault, and later re-identify them under access controls. It explicitly supports protecting data sent to external LLMs.
For example:
Before:
"John Smith at [email protected] needs his $4,200 invoice corrected."
LLM sees:
"[PERSON_7] at [EMAIL_3] needs his [AMOUNT_12] invoice corrected."
Your application receives:
"[PERSON_7] at [EMAIL_3] needs his [AMOUNT_12] invoice corrected."
Vault restores:
"John Smith at [email protected] needs his $4,200 invoice corrected."
Skyflow supports configurable tokenization/de-identification and can operate on text, PDFs, documents, images, and audio. Skyflow Docs It also offers different deployment models, including VPC and BYOC options, which can matter if the vault itself must remain under your security boundary.
If you don't need a managed vault, Microsoft Presidio is a strong building block. It's open source and provides PII detection plus anonymization/de-anonymization, with operators such as replacement, masking, redaction, hashing, and encryption.
You could deploy it entirely inside your infrastructure:
┌──────────────────────┐
│ Your application │
└──────────┬───────────┘
│
sensitive prompt
│
┌──────────▼───────────┐
│ Privacy gateway │
│ │
│ Presidio / custom │
│ PII detection │
│ tokenization │
│ policy enforcement │
└──────────┬───────────┘
│
anonymized prompt
│
┌──────────▼───────────┐
│ Public LLM API │
│ OpenAI / Anthropic / │
│ Gemini / etc. │
└──────────┬───────────┘
│
anonymized answer
│
┌──────────▼───────────┐
│ Re-identification │
│ + policy checks │
└──────────┬───────────┘
│
safe response
Presidio can be installed as Python packages or containerized services, making it practical for a self-hosted gateway.
I would not simply redact everything. For LLM workloads, deterministic tokens are usually better:
John Smith→PERSON_001Acme Corporation→COMPANY_001[email protected]→EMAIL_001That lets the model reason about relationships consistently across a conversation while never receiving the actual identity.
I'd also make the gateway handle more than PII:
My recommendation: if this is an enterprise product and you want a real "vault," start by evaluating Skyflow. If you're building infrastructure yourself and want maximum control/cost efficiency, use Presidio + a small policy/token vault + an LLM proxy.
If you tell me whether you're looking for self-hosted, SaaS, or something you can deploy in AWS/Azure/GCP, I can narrow this down to 3–5 concrete products and compare their architecture, pricing, deployment, and LLM integrations.
To safely leverage public LLM APIs (like OpenAI, Anthropic, or Gemini) without leaking Personally Identifiable Information (PII) or sensitive enterprise data, you need a **PII Proxy / Masking Architecture**.[[1]](https://dev.to/bspann/presidio-as-an-llm-guardrail-gcf) The standard design pattern intercepts your…
To safely leverage public LLM APIs (like OpenAI, Anthropic, or Gemini) without leaking Personally Identifiable Information (PII) or sensitive enterprise data, you need a PII Proxy / Masking Architecture.
The standard design pattern intercepts your payload locally, strips or tokenizes sensitive data into placeholders, sends the sanitized payload to the public LLM, and then deanonymizes/restores the response on its way back to your application.
Top Open-Source & Enterprise Options for LLM Data Anonymization
How the Architecture Works (The PII Proxy Pattern)
text``` [User / App] │ (Sends prompt with "Call John Doe at 555-0199") ▼ [Privacy Proxy / Vault Layer] │ (Detects PII & replaces with tokens: "Call <PERSON_1> at <PHONE_1>") ▼ [Public LLM API] (Processes only the anonymized text) │ (Returns response referencing "<PERSON_1>") ▼ [Privacy Proxy / Vault Layer] │ (Swaps tokens back to "John Doe") ▼ [User / App] (Receives complete, contextual response)
---
<FollowUp>
To help you zero in on the right implementation, tell me:
* Are you looking for a **self-hosted open-source stack** (like Microsoft Presidio + LiteLLM) or a **managed enterprise vault**?
* What **programming language or framework** is your backend built on?
</FollowUp>
Use code with caution.
Yes. What you’re describing is essentially a **privacy gateway/vault in front of public LLM APIs**: **Your app → privacy vault → anonymized/tokenized prompt → OpenAI/Anthropic/Gemini/etc. → tokenized response → vault → re-identified response** ### Best fits
Yes. What you’re describing is essentially a privacy gateway/vault in front of public LLM APIs:
Your app → privacy vault → anonymized/tokenized prompt → OpenAI/Anthropic/Gemini/etc. → tokenized response → vault → re-identified response
| Option | Best for | What it does |
|---|---|---|
| Skyflow | Production/enterprise | A true privacy vault: detects sensitive data, replaces it with tokens, stores the mapping, and can re-identify it after the LLM responds. docs.skyflow.devwww.skyflow.com |
| Microsoft Presidio | Self-hosted/open source | Detects and anonymizes PII locally using replacement, masking, redaction, hashing, or encryption. You build the vault/token mapping and LLM proxy around it. github.com |
| Skyflow + your own LLM proxy | Strongest architecture | Skyflow handles the sensitive-data vault/tokenization while your gateway controls which public models receive the sanitized request. Skyflow explicitly supports this inference pattern. docs.skyflow.devwww.skyflow.com |
If you want a ready-made privacy vault, I'd investigate Skyflow first. Its design is unusually close to your requirement: sensitive values are detected and replaced with deterministic tokens before being sent to an external LLM, while the original values remain in the vault and can be restored afterward under access controls.
If you need self-hosted/on-prem and don't want the vault provider itself seeing the plaintext, I'd use Presidio as the detection/anonymization layer and build a small gateway around it. Presidio can run as containerized services, and its anonymizer supports reversible encryption as well as replacement/redaction.
One important caveat: PII detection isn't perfect. Presidio itself warns that it cannot guarantee detection of all sensitive information, so a production gateway should combine NER/PII detection with regexes, custom dictionaries, allow/deny rules, and ideally an output scanner.
If you tell me whether you want (1) SaaS, (2) self-hosted, or (3) open-source, I can compare the best 5–10 options specifically on anonymization quality, reversibility, deployment, pricing, and whether the vault provider ever sees plaintext.
To route data safely through public LLM APIs (like OpenAI, Anthropic, or Groq) without leaking sensitive customer information or PII, you need a **Privacy-First LLM Gateway or Local Proxy with an In-Memory/Encrypted…
To route data safely through public LLM APIs (like OpenAI, Anthropic, or Groq) without leaking sensitive customer information or PII, you need a Privacy-First LLM Gateway or Local Proxy with an In-Memory/Encrypted Vault.
The architecture for this pattern follows a specific flow: Intercept → Detect PII → Tokenize/Mask → Proxy to LLM → De-anonymize Response.
Top Open-Source & Enterprise Solutions
How to Build a Lightweight Custom Version (Python + Presidio)
If you prefer rolling your own local proxy middleware, you can combine Microsoft's open-source Presidio analyzer with an in-memory dictionary or encrypted vault:
presidio-analyzer and presidio-anonymizer to scan input text, extract entities (names, emails, financial records), and replace them with unique placeholders (<PERSON_1>, <EMAIL_1>).Placeholder $\rightarrow$ Original Value in a secure, ephemeral in-memory vault or an AES-encrypted local cache for the duration of the session.If you want to dive deeper, let me know:
If you need a privacy vault or proxy that intercepts prompts, strips out Personally Identifiable Information (PII) and sensitive data, and then forwards the anonymized payload to public LLM APIs (like OpenAI, Anthropic, or Cohere), there are several robust open-source tools and enterprise platforms designed…
If you need a privacy vault or proxy that intercepts prompts, strips out Personally Identifiable Information (PII) and sensitive data, and then forwards the anonymized payload to public LLM APIs (like OpenAI, Anthropic, or Cohere), there are several robust open-source tools and enterprise platforms designed specifically for this.
Here are the top options broken down by how you want to deploy and use them:
Open-Source & Self-Hosted Gateways
Enterprise & Managed Privacy Vaults
If you can tell me:
I can give you a quick configuration example or recommend the best integration path for your setup.
If you mean a **privacy vault/proxy that sits between your applications and public LLM APIs**, you’re looking for a **PII de-identification gateway** (sometimes called an AI privacy gateway, LLM firewall, or anonymization proxy). A solid architecture looks like this: ```
If you mean a privacy vault/proxy that sits between your applications and public LLM APIs, you’re looking for a PII de-identification gateway (sometimes called an AI privacy gateway, LLM firewall, or anonymization proxy).
A solid architecture looks like this:
User/App
|
v
Privacy Vault Gateway
|
+--> Detect sensitive data (PII/PHI/secrets)
|
+--> Replace with tokens or synthetic identities
|
+--> Store reversible mapping in encrypted vault
|
v
Public LLM API
(OpenAI, Anthropic, Google, etc.)
|
v
Response
|
+--> Restore original entities (optional)
|
v
User/App
Key capabilities to look for:
The gateway should detect:
An open-source option is Microsoft Presidio, which provides analyzer and anonymizer components for detecting and transforming sensitive data.
Avoid simple redaction if the LLM needs context.
Example:
Before:
Email John Smith at [email protected] about account 884392.
Sent to LLM:
Email PERSON_001 about ACCOUNT_001.
Vault:
PERSON_001 → John Smith
ACCOUNT_001 → 884392
The response can then be restored.
Presidio supports operators such as replace, mask, hash, redact, and encryption-based transformations.
The vault itself should:
Useful controls:
Build-your-own stack
Managed privacy proxy products There are vendors offering this exact “before the LLM” pattern, such as:
For a production enterprise deployment, I would generally design it as:
Application → Privacy Gateway → LLM API
not:
Application → LLM API → “hope the provider handles privacy”
A few questions would determine the right design:
Yes. What you’re describing is essentially a **privacy gateway / de-identification vault**: **Your app → privacy vault → anonymized prompt → public LLM API → anonymized response → vault → restored response** ### Best options
Yes. What you’re describing is essentially a privacy gateway / de-identification vault:
Your app → privacy vault → anonymized prompt → public LLM API → anonymized response → vault → restored response
Skyflow — best fit if you want a managed enterprise vault
Microsoft Presidio — best open-source foundation
A self-hosted privacy proxy
If you're handling real customer/company confidential data, I'd favor:
┌──────────────────────┐
User/App ───────►│ Privacy Gateway │
│ │
│ 1. Detect PII │
│ 2. Tokenize │
│ 3. Store mapping │
│ 4. Audit/policy │
└──────────┬───────────┘
│
"Contact [PERSON_42]
at [EMAIL_17]..."
│
▼
Public LLM API
│
▼
"Tell [PERSON_42]..."
│
▼
┌──────────────────────┐
│ Re-identification │
│ [PERSON_42] → Bob │
└──────────────────────┘
The important distinction is tokenization rather than simple redaction. If you replace "John Smith" with [PERSON], the model loses useful context. A stable token such as [PERSON_42] lets the model reason about the same person consistently throughout the conversation, while the actual identity remains outside the LLM.
For a self-hosted stack, I'd look at Presidio + Redis/Postgres for the encrypted mapping + an OpenAI-compatible gateway. Presidio provides the detection/anonymization layer, while your vault owns the reversible mapping.
One caveat: anonymization isn't automatically the same thing as privacy. You also want to prevent secrets, proprietary source code, credentials, internal URLs, and unique business identifiers from escaping—not just names and email addresses. Recent research specifically finds that PII redaction performs much better for PII than for proprietary code, so your policy layer should cover both.
If you tell me whether you want (a) an existing product, (b) open-source/self-hosted, or (c) something you can deploy as an API in front of OpenAI/Anthropic/Gemini, I can narrow this to the best 3 choices and compare their architecture, pricing, and security model.
To protect sensitive data before it reaches public LLM providers like OpenAI, Anthropic, or Google, you need an **LLM Privacy Gateway / Proxy** with an integrated, reversible tokenization and de-identification engine.[](https://github.com/rohansx/cloakpipe)…
To protect sensitive data before it reaches public LLM providers like OpenAI, Anthropic, or Google, you need an LLM Privacy Gateway / Proxy with an integrated, reversible tokenization and de-identification engine.
Instead of trusting a third-party API with raw data, these tools intercept outgoing requests locally or inside your private VPC, redact or tokenize Personally Identifiable Information (PII) and secrets, forward the sanitized prompt to the LLM, and unmask the response locally on its way back to your application.
Top Open-Source & Self-Hosted Solutions
Enterprise & Managed Data Privacy Vaults
If you can tell me whether you prefer an open-source self-hosted proxy (like Presidio or AI Security Gateway) or a managed enterprise vault (like Skyflow), I can help provide a deployment architecture or code snippet tailored to your stack.