Editorial translation; the original Portuguese version prevails in case of discrepancy.

How to check a piece yourself

None of this asks you to trust us. Every piece publishes what is needed to redo the check on your own, in five steps. You don't need to be a journalist or a programmer; the hash step uses a single command.

1. Open the source

Scroll down to the Sources list, at the foot of the piece. Each item has a title, origin, date and the original link. The bracketed numbers in the text — [1], [2] — lead to the matching item. Open the document and read the excerpt in its own context, not ours.

2. Compare the excerpt

Each source carries the literal excerpt we used, in quotation marks. On the document's page, search for that excerpt using your browser's search: Ctrl+F on Windows and Linux, Cmd+F on a Mac. Search for the first five or six words, not the whole sentence: accents, typographic quotation marks and line breaks get in the way of an exact match. If the excerpt does not appear, or says something else, the mistake is ours and we want to know about it.

3. Check the PDF's hash

When the source is a PDF, we publish the sha256 of the file we downloaded. It's a fingerprint: if a single byte changes, the whole number changes. To check it, download the PDF and run this in a terminal:

• macOS or Linux: shasum -a 256 file.pdf
• Windows (Command Prompt): certutil -hashfile file.pdf SHA256 Compare the result with what is in the piece. If it matches, it's the same file we read. If it doesn't match, the file changed after our capture, or you downloaded a different one. Both possibilities matter, and the second one is news.

4. See the archived copy

Pages change and disappear. That is why each source carries, when one exists, the address of the copy in the internet's public archive, the Wayback Machine (web.archive.org). Open the copy and compare it with today's page: you can see whether the text was edited after publication, and when.

You can also archive any page yourself, at Save Page Now, and keep the address with the date. It's the simplest way to have proof of what was written today.

5. Ask for a correction

Found a mistake? Write to contato@revalida.info with the address of the piece, the wrong excerpt and, if you have it, the document that shows the error. We review it within 48 business hours. If the mistake is ours, the correction goes to the top of the piece, dated, and is added to the corrections page — we do not correct in silence.

What cannot be checked

Some documents only open for subscribers, and some sites block automated access. When that happens, the piece states that the check was done by reading, not by machine. That notice sits right on the source itself, so you know exactly where the chain of evidence is weakest.