PDF Editor Online

How to Edit a PDF Online

Features

What Is a Browser-Based PDF Editor?

A browser-based PDF editor allows you to modify PDF files without installing any software — the editing happens directly within your web browser. Traditional PDF editing requires expensive software like Adobe Acrobat (starting at $20+/month) or installing a desktop application. For light editing tasks like adding text, inserting a signature, or marking up a document, a browser-based editor provides the same functionality at no cost, accessible immediately from any device.

This editor uses two powerful libraries: PDF.js (by Mozilla) to render the current page onto a canvas so you can see and interact with the content, and pdf-lib to embed your annotations as native PDF drawing instructions when you download. This approach preserves the original page content at full quality while adding your new content on top as a separate layer. After downloading, if you want to make the annotations permanent and unremovable, use the PDF Flattener.

Adding Text to a PDF

The text tool in this editor adds text boxes as new content drawn on the PDF page. Click the T tool, then click on the canvas where you want the text. A popup appears where you type your text and configure the font (Helvetica, Times, Courier), size (8–72pt), and color. After clicking Insert, the text appears on the canvas and can be repositioned with the Select tool.

This is different from editing existing text in the PDF — text added this way is new content drawn over the original, not a modification of the existing text content stream. For replacing existing text, switch to the "Edit Existing" tool which attempts to identify and overlay existing text blocks for editing. The text addition approach is ideal for completing templates, adding labels, inserting captions, or adding information that was missing from the original PDF.

Adding Signatures to PDFs

The signature tool lets you draw a handwritten signature using your mouse or trackpad on a signature pad (a canvas modal that pops up). Once you save the signature, it is stored as a canvas image for the current session. Each click on the PDF canvas places the saved signature image as a new annotation. You can resize and reposition it using the Select tool.

The signature is embedded into the PDF as an image drawn at the signature annotation's position. This creates a visual representation of a handwritten signature that looks exactly like a physical signature would appear when scanned. Note that this is a visual signature — it does not include cryptographic signature data and does not satisfy legal requirements for electronic signatures in jurisdictions that require qualified or advanced electronic signatures (like eIDAS in Europe). For legally compliant e-signatures, use a dedicated e-signature service.

Redact Tool — Black Out Sensitive Information

The Redact tool (⬛) lets you drag across any area of the PDF to draw a solid black rectangle that permanently covers the underlying content in the downloaded file. Common use cases include hiding bank account numbers on financial statements before sharing them, blacking out personal addresses in lease agreements shared with third parties, and covering confidential figures in reports distributed to a wider audience.

The black redaction box is embedded directly into the PDF as a filled rectangle instruction using pdf-lib, so it appears in every PDF viewer without requiring any special rendering. You can place multiple redaction boxes across different areas of the page, undo them with the ↩ button before downloading, or switch to Select mode to move a box to a different position. Important caveat: the underlying original text still exists in the PDF data structure. A sophisticated user with a hex editor or advanced PDF tool could technically remove the rectangle and expose the original. For court filings, FOIA responses, or GDPR-compliant redaction, use a purpose-built redaction tool that permanently removes the content from the file structure.

Who Actually Reaches for This

Freelancers and small business owners marking up a client's PDF proof with arrows and comments instead of describing feedback in a separate email that's easy to lose track of. HR and office staff completing a scanned form that has no fillable fields — typing values directly onto the page where a blank line expects them. Anyone signing a lease, contract or waiver who needs their signature on the document today, not after mailing a printed copy back and forth. Small teams reviewing a shared report who black out a client's account number or a colleague's personal address before forwarding it more broadly, without needing a copy of Acrobat Pro for something that takes thirty seconds here.

Why the Check and Cross Stamps Get Their Own Font-Metric Handling

Placing a ✓ or ✗ mark so it lines up exactly where you clicked sounds trivial until you actually try it — text baselines don't sit where a naive top-left placement would assume, and a stamp that's even a few pixels off vertically looks visibly wrong once the PDF is printed or reviewed at full size. This editor renders each stamp to an offscreen canvas first, using Arial's actual alphabetic-baseline metrics (roughly 81% down from the top of the character's em-box) to calculate the correct vertical offset, then embeds the result as a PNG at the precise position that matches where the stamp visually appears in the editor. That's a level of care most quick annotation scripts skip entirely, which is usually the reason a stamp from a simpler tool looks slightly high or low once you zoom in.

Everything Runs on Your Own Device

PDF.js and pdf-lib are both loaded once and then execute entirely inside your browser tab — the file you drop in, every annotation you place, and the final edited PDF that downloads are all handled locally, with nothing transmitted to a ToollyX server or anywhere else at any point. That matters more than usual for a PDF editor specifically, since the documents people annotate here are often the exact ones they'd least want passing through a third party: signed contracts, financial statements, medical forms, anything with a redaction box drawn over it for a reason. The tool keeps working offline once the page has loaded, which is also a fast way to confirm for yourself that nothing is being sent anywhere.

When Not to Use This Tool

The PDF Editor is designed for visual annotation — adding content on top of existing pages. It cannot: rearrange or delete existing text content, change existing fonts or images, modify the underlying PDF structure, or create PDFs from scratch. For those needs: use Page Reorder to rearrange pages, use a design tool to create new PDFs, or use Watermark PDF to add repetitive text to all pages. For filling standard form fields rather than overlaying text on top of them, the PDF Form Filler provides a better experience.