Posting a Document Online to Ask for Advice: What to Mask First
Before you post a lease, fine or bill on a forum for advice, mask names, addresses and reference numbers. Here is what you can safely keep.
Jane Example photographs a parking fine and posts it on a forum, asking if it looks normal. Before you post any document publicly, mask the names, addresses and reference numbers that point back to a real person. Keep only what helpers actually need: the clause, the amount, the date.
This guide covers the EU, with notes for the UK and the US, as of September 2026. It is not legal advice. When a rule depends on your own situation, ask a data protection authority or a lawyer.
Why is a public post different from sending a document to one person?
Sending a file to your accountant is private and temporary. Posting the same file on a forum, Reddit or a Facebook group is public, and it does not stay under your control. Strangers can read it, save it, quote it in their own reply, or screenshot it before you can even edit the post.
- Search engines can index a public post and its images, so a name inside a photo can later surface in a search.
- Other members can download, reshare or quote your post in a new thread you do not control.
- Forums and groups keep old posts and can show them to anyone, not just the community you first had in mind.
- A public post can outlive the problem it was meant to solve, staying online long after you found your answer.
Which details let a stranger identify you?
A document rarely reveals you through one detail alone. It is usually a combination, such as a full name next to a city, or an account number next to a company logo. Read the whole page before you post it, not just the obvious blank marked name.
- Full names: yours, your family's, your landlord's, your doctor's or your employer's.
- Your complete postal address, including a building, floor or apartment number.
- Case, claim, customer, policy or contract numbers. With the right access, staff can look one up.
- Barcodes and QR codes. They often encode the same reference number printed nearby as plain text.
- Letterheads, logos and email footers that name your employer, landlord, bank or clinic.
Before you post, ONYRI Sanitize can help. In the browser, it finds names, addresses, IBANs and reference numbers. Its Search the document tool then masks every copy of a case number in one click. The download is a flattened PDF, or a PNG for a photo. Limit: detection is not exhaustive, so check the preview yourself before you post.
What should you keep so people can actually help?
Helpers can only answer what they can see. Cutting too much turns your post into a guessing game. Keep the exact wording of the clause or fine, plus the amounts and dates. Also keep the type of sender, such as a debt collector or your landlord.
- The exact clause, paragraph or fine amount you are actually asking about.
- Dates: when the letter was sent, and when a deadline falls.
- The general type of sender, such as a bank, a public agency, a landlord or a hospital.
- The country or region, since rules for leases, fines or taxes differ from one place to another.
Photo, screenshot or PDF: which is safest to post?
A phone photo often captures your desk, a second document, or your own reflection in a glass table. A full screenshot can catch a notification banner with someone else's name on it. A cropped, single-page image or PDF gives you far more control over what actually leaves your device.
- Crop the image down to the one page or section people actually need to see.
- Check the edges for a second document, a calendar or a notification sitting underneath.
- Cover names, addresses and reference numbers before you take the screenshot, never after.
- Save the result as a plain image or PDF, not a live file that others can still edit.
What should you mask, document by document?
| Document | Mask | Keep |
|---|---|---|
| Lease | Your name, landlord's name, address, tenant reference | The disputed clause, the rent amount, the notice period |
| Parking or traffic fine | Name, address, plate number, fine reference number | The offence code, the amount, the date and location type |
| Tax notice | Name, address, tax or social security number | The tax year, the amount owed, the calculation lines |
| Contract | Names, addresses, signatures, contract number | The clause in question, the amounts, the term length |
| Medical bill | Patient name, address, insurance member number, any diagnosis or procedure code | The amount billed, the date of service, what insurance covered |
| Bank letter | Name, address, account number or IBAN, customer number | The fee type, the amount, the reason given |
Does deleting your post remove it everywhere?
No. Deleting your own post removes it from that page, but not necessarily from everywhere it has already been. Google's own Search Help says that content removed from Google Search 'might still be on the internet'. It can still be found through links, social media or other search engines. The original page stays untouched unless its owner removes it too.
A little masking before you post costs a minute. Chasing copies after the fact can cost far more. Cover the names, the address and the numbers that point back to you or to someone else. Then let the clause and the amount do the talking.
Frequently asked questions
Do I need to mask reference or case numbers, not just my name?
Yes. A case, claim or customer number is often enough for the sender's own staff to open your file. Treat it like a password: mask it even once your name is gone, because it can still point straight back to your record.
What if the people helping me really need my exact address?
That is rare. Most questions about a lease, a fine or a bill can be answered with the city or region, the amount and the clause. Keep the full address only if a local rule genuinely depends on it, and just say so in your text instead of showing the document.
Does deleting my post also remove it from Google?
Not automatically. Google explains that removing a result from Google Search does not delete the page itself. The content can still be found through other links or search engines. You, or the site hosting your post, would still need to remove the original.
Is a masked document safe to post publicly forever?
Masking the obvious identifiers lowers your exposure, but it is not a guarantee for good. Combine a few details from the same post, or from other posts by the same username. A determined reader might still narrow down who you are. When in doubt, mask more, not less.
Sources & references
- Social media: how to use it safelyNational Cyber Security Centre (NCSC, UK)
- Remove your personal information from Google SearchGoogle Search Help
- Identity Theft and Online SecurityFederal Trade Commission, Consumer Advice
- Protect Your Personal Information From Hackers and ScammersFederal Trade Commission, Consumer Advice