PDF Prompt-Injection Detector

Find text that's invisible to you but readable by LLMs.

Drop a PDF here, or click to choose

Your file is analysed in memory and never stored. PDF only, up to 25 MB.

Don't have one handy?

What it catches

Opacity-0 text

Glyphs drawn with fill opacity 0 (ExtGState /ca) — extracted, never painted.

Invisible render mode

Text render mode 3 (invisible) or 7 (clip only) puts nothing on the page.

White / tiny / off-page

Background-coloured, sub-pixel, or off-canvas text — flagged as heuristics.