Use AI without
leaking private data

Caesar automatically removes personal and confidential information from your prompts, lets you use any AI safely, then restores the answer with your real data — all in your browser.

ChatGPT logo
ChatGPTGPT-5.5 · chatgpt.com
Secure
You're typing — protected before send
Reply to Sarah Johnson at sarah.johnson@acme.com about the invoice paid with card 4111 1111 1111 1111. Use key sk-live-9f8a7b6c.
Caesar redacts personal data before anything leaves your browser.
Works with any LLM

Exactly what gets protected

The same text before and after — only the sensitive values change, everything else stays intact.

Original what you'd paste

Prepare a billing entry for Michael Reyes (DOB 02/23/1986), residing at 4821 Cedarwood Rd, Austin TX. Insured by BCBS (ID: TXB-0441). Contact at 512-555-0148 or m.reyes@gmail.com. Pay via card 4539 1488 0343 6467 using API key sk-live-9f2b.

Anonymized safe to send to any AI

Prepare a billing entry for [NAME_1] (DOB [DOB_1]), residing at [ADDRESS_1]. Insured by [ORG_1] (ID: [CLAIM_1]). Contact at [PHONE_1] or [EMAIL_1]. Pay via card [CARD_1] using API key [KEY_1].

Entities Found9
Ready to copy to LLM

Local-first, always

100% local processing

All masking happens on your device. Nothing is sent away.

Real-time detection

Sensitive data is spotted in milliseconds as you type.

Reversible & private

Restore answers locally — your mappings never sync raw.

Anonymize on the way out, restore on the way back

It's a round trip: protect what you send, then decode the answer so it makes sense again — without leaking anything.

Outgoing: anonymized

Sensitive values become placeholders before your prompt ever leaves the browser.

Incoming: restored

Paste the AI's reply back and Caesar swaps placeholders for your real data — locally.

You hold the key

The mapping that restores your data is stored only on your device. No server sees it.

Claude logo
ClaudeClaude 4.8 Opus · claude.ai
Anonymized
You · sent anonymized
Analyze transaction for card [CARD_1] belonging to [NAME_1].
Claude · with placeholders
The transaction on card [CARD_1] for client [NAME_1] is approved. Notify them at [EMAIL_1].
LLM only sees secure placeholders
Placeholders are swapped back to your real data locally — never on a server.

Four steps to a private AI workflow

Step 1

Paste your prompt

Drop in any text with sensitive details.

Step 2

We anonymize it

Sensitive values become safe placeholders, locally.

Step 3

Use any AI

Send the safe prompt to ChatGPT, Claude, Gemini.

Step 4

Restore the answer

Paste the reply back — your real data returns.

Tailored to your industry

Use the full ruleset or switch to a profile tuned for your field — then fine-tune every data type.

General

Standard data protection for general writing and chat. Protects basic PII like names, emails, and credentials.

Legal

Strict protection for legal documents, briefs, and client consults. Masks client details and case IDs.

HR / Recruitment

Tailored for screening candidates, reviews, and payroll logs. Redacts or masks applicant names, contact info, and sensitive data.

Healthcare

HIPAA-aligned rules. Strictly blocks medical identifiers and masks patient data.

Finance

Optimized for banking, trading, and transaction datasets. Blocks financial instruments and card numbers.

Developer / Security

Protects API keys, passwords, certificates, JWTs, IPs, and internal repository paths.

Education / Research

Protects student records, research projects, and academic identifiers.

Consulting

Designed for consultants handling multiple client contexts. Focuses on protecting client names and project specifics.

What Caesar detects

Dozens of data types out of the box — grouped, fully customizable, and tuned for 10+ languages.

Identity

  • Names
  • National / Social IDs
  • Passport numbers
  • Age
  • Vehicle VIN

Contact

  • Email addresses
  • Phone numbers

Financial

  • Credit cards
  • IBAN
  • Bank accounts
  • Org / Tax numbers
  • Crypto wallets

Credentials

  • API keys
  • JWT tokens
  • Private keys
  • Passwords / secrets
  • Access tokens

Location

  • Postal addresses
  • Locations
  • IP addresses
  • MAC addresses
  • GPS coordinates

Other

  • Company names
  • Dates
  • URLs
  • Device / UUIDs
Detects names, IDs & formats in
EnglishEspañolDeutschFrançaisItalianoPolskiPortuguêsNederlandsРусскийУкраїнськаČeština中文

Frequently asked questions

Detection and masking run entirely in your browser. Sensitive values are replaced with placeholders before you ever send a prompt to an AI service — your raw text and the mapping that restores it never leave your device.
Yes. Every account includes a free monthly quota with full access to all data types and industries. If you need more volume, you can upgrade to Pro at any time.
Names, emails, phone numbers, addresses, national IDs, passports, credit cards, IBANs, bank accounts, API keys, tokens, passwords, IP addresses and more — across 10+ languages, fully customizable per industry.
Caesar keeps a local mapping of each placeholder to its original value. Paste the AI's response into the Restore tab and your real data is filled back in automatically — locally, never on a server.
The web workspace works with any AI — just copy the safe prompt. The browser extension adds inline protection on ChatGPT, Claude, Gemini, Grok, DeepSeek and more.
No raw prompt text or restore mappings are uploaded. Only your account and settings are stored. Detection is local-first by design.

Start protecting your prompts

Sign in with Google or GitHub — free quota included.