How it works
We use pdf-lib's page.drawText with the built-in Helvetica font. Original content is untouched — your text is drawn on top.
FAQ
Why ASCII only? PDF's 14 standard fonts (Helvetica, Times, Courier and friends) are built in to every reader and only encode Latin-1 characters. Embedding a Unicode font (e.g. Noto Sans for Korean or Chinese) would balloon the output by 3–10 MB and require a font upload step that we deliberately avoid. For non-ASCII annotations, place them in your authoring tool first.
How do x/y coordinates work? PDF's coordinate system has the origin (0, 0) at the bottom-left corner of the page, measured in points (1/72 of an inch). A US Letter page is 612 × 792 points. So `x = 72, y = 720` puts text 1 inch from the left edge and 1 inch from the top.
Can I add text to every page at once? Not in this tool — for repeating text on every page (e.g. a header or watermark), use the Watermark or Page Numbers tools. This tool is for one-off annotations on a specific page.