Free means Instant singles — not a surprise paywall on the download button
Eligible everyday files stamp without an account. The architecture is local pdf-lib, so we are not metering a cloud GPU. That is why there is no email gate. Premium exists for multi-file queues and ~100MB+ documents that exhaust a tab — we label that on the batch spoke rather than watermarking your output until you pay. Drag-and-drop on desktop; file picker on phones. Text or PNG, opacity and grid. Quality: overlay, not print-to-image, so type stays sharp. Competitors that flatten to JPEG to “stamp free” are a different (worse) product. Locked-down office PCs can use the browser. Close the tab and there is no copy on Convertify4u because none was sent. If you only need a footer on page one, split that page first — this tool repeats one recipe on every sheet. Print a test page before you stamp a 40-page packet; screenshots of PDF apps often show overlays lighter than toner will.
What stays free
Typical single PDFs: overlay and download, no signup. Instant labeled path — unlimited in the sense that we are not counting daily cloud conversions.
What Premium unlocks
Folder queues and stubborn huge files. OCR is a different Convertify4u product, not this stamper.