To black out text safely, the final image must no longer contain the original text pixels. A solid rectangle that is burned into a new image file does this; a temporary annotation, highlight, or document layer may not.
You can use Redact Sensitive Info for free in your browser. There is no account or watermark, and the image itself never leaves your device.
How to permanently black out text
- Load the image by choosing a file, dragging it onto the page, pasting from your clipboard, or entering an image URL.
- Turn on box mode with the B key.
- Drag over the entire line or field you need to remove. Leave a small margin around the characters so antialiased edges are covered.
- Repeat for names, numbers, labels, and any surrounding context that could identify the hidden value.
- Download and inspect the resulting PNG before sharing it.
The download is rendered as a new image. The black boxes become permanent pixels rather than separate shapes someone can select and delete.
Text people commonly forget to redact
The sensitive part is not always the largest or most obvious text. Check for:
- Names in navigation, breadcrumbs, and browser tabs
- Email addresses in headers and autocomplete suggestions
- Customer, patient, employee, or student identifiers
- Bank balances, card digits, and transaction references
- URLs containing tokens or private record IDs
- File paths that reveal usernames or company names
- Wi-Fi passwords, API keys, and recovery codes
- Dates and timestamps that can identify an event
Also consider whether nearby labels reveal the meaning of a redacted value. Hiding a number while leaving “Social Security number” and its final digits visible may still disclose too much.
Black boxes versus marker tools
Some markup applications simulate a black marker using a partly transparent stroke. Layering the stroke can make it look opaque on your screen, but pixel inspection or simple contrast adjustments may reveal the text beneath it.
Use a fully opaque redaction and export a flattened image. Avoid relying on highlights, translucent brushes, emoji, or shapes added in a document editor unless you have verified the result is permanently flattened.
Verify before you send
Open the downloaded image in a separate viewer. Zoom in, confirm that no letters extend beyond the boxes, and verify that you selected the exported copy. If you are preparing a screen capture, the complete checklist in how to redact a screenshot covers notifications, tabs, avatars, and other easy-to-miss details.