---
title: "Adding a text watermark"
description: "Learn how to add text watermarks to your generated PDF document using Ruby and the Net::HTTP library. With this guide, you'll be able to add watermarks on top of your generated PDFs easily with a quick request to PDFShift's API."
language: 'Ruby'
library: 'Net::HTTP'
property: 'watermark'
output: 'pdf'
related: ['adding-an-image-watermark', 'protecting-the-generated-pdf']
default: true
---

In this guide, we'll walk you through the process of adding text watermarks to your PDF files, using PDFShift's API.

Adding a watermark to your PDF can be done by adding the `watermark` object to your query. Adding a text allows you to customize its content and PDFShift's API provides a few properties to help you customize the visual aspect, such as the font size, color, and position.

```ruby
require 'net/http'
require 'uri'
require 'json'

# You can get an API key at https://pdfshift.io
api_key = 'sk_xxxxxxxxxxxx'

params = {
    'source' => 'https://www.example.com',
    'watermark' => {
        'text' => 'PROTECTED DOCUMENT',
        'offset_x' => 'center',
        'offset_top' => 'top'
    }
}

url = URI("https://api.pdfshift.io/v3/convert/pdf")
http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request['Content-Type'] = 'application/json'
request['X-API-Key'] = api_key
request.body = params.to_json

# Send the request and handle the response
response = http.request(request)

# write response to a file nammed "result.pdf"
File.open('result.pdf', 'wb') { |f| f.write(response.body) }

# Print a success message
puts 'The PDF document was generated and saved to result.pdf'
```

You can customize the text watermark by applying the following properties:

 * `font_size`: The size of the text. An integer value in pixels. Defaults to 16.
 * `font_family` : The font family to be used. Defaults to Helvetica.
 * `font_color` : The color of the text. A hexadecimal color value. Defaults to '000000'.
 * `font_opacity` : The opacity of the text. A float value between 0 and 100. Defaults to 100.
 * `font_bold`: A boolean to set the text as bold. Defaults to false.
 * `font_italic`: A boolean to set the text as italic. Defaults to false.

You can also customize the position of the text watermark by applying the following properties:

 * `offset_x`: The horizontal position of the text. Can be 'left', 'center', 'right', or a specific value in pixels. Defaults to 'center'.
 * `offset_y`: The vertical position of the text. Can be 'top', 'middle', 'bottom', or a specific value in pixels. Defaults to 'center'.

For the offset positions, we accept a value in integer which will be translated to pixels, but you can also pass a unit such as 'px', 'in', 'cm', 'mm', 'pt'.

For example:

```json
params = {
    "source": "https://www.example.com",
    "watermark": {
        "text": "PROTECTED DOCUMENT",
        "offset_x": "5cm",
        "offset_top": "15mm"
    }
}
```