Redact text online, without uploading it
This page is preset to Blocks: matched values are replaced with solid ▪ characters, the way a marker pen would. Unlike a marker pen — and unlike a black rectangle drawn over a PDF — the original characters are genuinely gone from the output, because the output is a new string built from the parts you kept.
Blocks are one-way. If you need to paste the text into a model and then restore the real values afterwards, switch to Tokens or Fake values in the toolbar above.
Your text
Safe to paste
Preset: irreversible block redaction — the original characters are dropped.
Mapping — 0 values (only visible in this tab)
| Placeholder | Real value | Uses |
|---|
Check a few rows before you paste — this is the fastest way to spot a detector that grabbed the wrong thing. Nothing here is stored or sent anywhere.
What to look for — 30 detectors, custom terms, exceptions
People & organisations
Government & health IDs
Financial
Technical & secrets
Location
Step 3 — paste the AI’s answer here to put the real values back
The model replies using the placeholders. Paste its answer below and every
[NAME_1] becomes the real name again — using the mapping held in this tab, which
is the only copy that exists.
How it works
- Open this page — the detectors are already set for “Redact text online”.
- Paste your text, or drop a .txt, .md, .csv, .json or .log file onto the panel.
- Check the highlights: every match is coloured by type, and one click keeps a type as-is.
- Copy the safe version and paste it into the AI tool of your choice.
- Paste the model’s reply back into step 3 to restore the real values.
The failure mode this avoids
The recurring redaction scandal is not a missing feature; it is redaction that looks finished but is not. Black rectangles drawn over a PDF sit on a layer above text that is still selectable. Screenshots blurred lightly can be sharpened. Text “deleted” in a document sometimes survives in tracked changes or in the file’s metadata. What all of those have in common is that the sensitive characters are still in the file.
A text redaction has a simpler standard to meet: the characters must not appear in the output. Copy the right-hand pane and what you paste is a string that never contained them. The rest is your job — check the highlighted left pane for anything the detectors missed, and remember that context can identify a person even when every name is gone.
What you can redact here
Thirty detectors cover people (names, emails, phones, @handles, companies), government and health identifiers (SSNs, passports, driving licences, medical record numbers, NHS and National Insurance numbers, Aadhaar, PAN), financial data (card numbers validated with the Luhn check, IBANs checked with mod-97, ABA routing numbers, account references, crypto wallets), technical secrets (provider API keys, JWTs, PEM private key blocks, IPs, MAC addresses) and locations (street addresses, postcodes, coordinates).
Anything a pattern cannot know goes in the custom-terms box: a project codename, an unusual surname, the name of a school, an internal system. Terms are matched on word boundaries and case-insensitively, and they are never saved anywhere.
Tips
- Drop a .txt, .md, .csv, .json or .log file straight onto the panel instead of pasting.
- The block length is capped at twelve characters so a long value cannot be guessed from the width of its redaction.
- Working with a PDF instead of text? Redacting a PDF properly means removing the underlying objects, not covering them — that is a different job from this one.
Detectors are pattern-based and imperfect: read the highlighted output before you paste it anywhere, and confirm your own confidentiality obligations against the current rules for your profession, employer or jurisdiction. Compiled 2026-07-29.
Frequently asked questions
Can the blocked-out text be recovered from what I copy?
Not from the output itself: it is a new string, and the redacted characters were never written into it. What you still control is everything else — the original text stays in the left pane until you clear it, and closing the tab discards it.
Do you keep a copy of what I redact?
No. Nothing is sent anywhere, and nothing is written to storage. The only thing this site remembers between visits is which detectors you switched on and which replacement style you prefer — never text, never custom terms, never mappings.
Is there a size limit?
The tool handles documents of a few hundred thousand characters comfortably. Above roughly 120,000 characters the coloured highlight layer switches off to keep typing smooth, but the redaction itself keeps working. Files opened from disk are capped at 5 MB.