PDF Editor

This PDF editor lets you add things on top of the pages of an existing PDF — text, pictures, white-out boxes, rectangles, highlights, freehand drawing and signatures — and save the result as a new PDF, without uploading the file anywhere. It is for the everyday jobs: filling in a form that has no fillable fields, adding a note or a date, covering an old phone number and typing the new one, highlighting a clause, or signing a letter.

It is an overlay editor, and that is the honest answer to the question most people have: it cannot change text that is already in the PDF. A PDF stores text as positioned glyphs, not as paragraphs, so reliable in-place rewording needs the original document. What you can do is cover the old words with White-out and type the replacement on top. White-out hides content visually only — the covered text stays in the file and can still be selected, copied or extracted, so never use it to hide confidential information.

How it works: pdf.js renders only the page you are looking at, at your screen's resolution, so even long documents stay light. Everything you add is kept in page points (1/72 inch) measured from the top-left of the page as it is displayed, which keeps placement correct on rotated pages and on pages whose coordinates do not start at zero. When you click Save PDF, pdf-lib opens the original file, leaves each page's existing content untouched and draws your additions after it: text as real text in an embedded font, images embedded once however often they are placed, and shapes and drawings as vector paths. Links, bookmarks, form fields and metadata are saved as they were.

Text uses the open-source Noto Sans fonts, fetched from this site only when you type: Latin (including accented letters), Greek and Cyrillic, plus Arabic, Hebrew and Devanagari (Hindi, Marathi, Nepali). Only the characters you use are embedded. Right-to-left lines are ordered with the core rules of the Unicode Bidirectional Algorithm and right-aligned; the box on screen is drawn from the same glyphs that go into the file, so what you see is what you get. Chinese, Japanese, Korean, Thai and emoji are not bundled — load your own .ttf or .otf font for those. Arabic, Hebrew and Devanagari look right, but copying them back out of the saved PDF may give scrambled characters.

Limits: one PDF up to 200 MB, images (PNG or JPG) up to 25 MB, your own font up to 30 MB, up to 2,000 added items, 5,000 characters per text box and font sizes from 4 to 200 pt. Password-protected or permission-locked PDFs are refused rather than saved broken. If the PDF carries a certificate-based digital signature, you are warned first: saving any change rewrites the file, so that signature stops validating.

Your PDF never leaves your device. It is read into the page, edited there and handed back as a download. You can check in your browser's developer tools: open the Network tab, edit and save, and no request carries your document (the page does load its own scripts, fonts and analytics, which never include your file).

1. The file's first bytes are checked for the PDF signature, then pdf-lib opens it: an encrypted file is refused, and each page's visible area (CropBox clipped to MediaBox, as pdf.js does) and /Rotate value are read. 2. pdf.js renders the current page at the displayed width × device pixel ratio (capped at 16 million pixels), and nothing else. 3. Each item you add is stored in page points from the top-left of the page as displayed. Text is laid out with fontkit using the bundled Noto fonts chosen per character by script; right-to-left runs are ordered with the core Unicode Bidirectional Algorithm rules (P2–P3, W1, W7, N1–N2, I1–I2, L1–L2). The preview draws the resulting glyph outlines. 4. On save, every item is drawn after the page's original content inside its own graphics state, through a matrix that maps display coordinates to the page's own coordinate system for rotations of 0°, 90°, 180° or 270° and any page origin. 5. Text is written with subset-embedded fonts, JPG and PNG images are embedded once each (JPG orientation tags respected), white-out and rectangles are filled or stroked paths, highlights use multiply blending at 40% opacity, and drawings are smoothed Bézier curves. The file is saved as <name>-edited.pdf.