PDF 编辑可以方便地从PDF文档的不同区域删除(remove)或隐藏敏感信息。(hide sensitive information)所选区域覆盖有编辑标记(redaction marks)或彩色框，以便永久删除存储在其后面的信息或数据（文本、链接、图像等）。
当您必须与某人共享PDF文档但又想保护该 PDF 的敏感数据时，PDF编辑会(PDF)非常有用。在这篇文章中，我们介绍了一些可以轻松编辑 PDF 的最佳免费工具。(free tools to redact PDF)在使用任何这些工具之前，您还应该保留原始PDF(PDF)文档的备份。
如何安全地编辑 PDF
这篇文章介绍了一些免费的PDF编辑软件和在线工具，可以将PDF 中的文本涂黑(black out text in PDF)：
- Sejda PDF 桌面
- PDF-XChange 查看器
- 平均PDF
- PDFzorro
- 小pdf
1] Sejda PDF桌面
Sejda PDF Desktop是一个PDF套件。它的主界面包含不同的工具，如压缩 PDF(compress PDF)、裁剪、合并、拆分、删除页面、提取页面(extract pages)、PDF水印等。您可以使用其PDF 编辑器工具(PDF Editor tool)在PDF页面中添加编辑标记。它没有使用黑色编辑标记，而是提供了一个白色选项(whiteout)来编辑 PDF。
这个工具很好用，但是这个软件的免费计划是有限的。您可以添加最多50 MB的 PDF 或最多200 页(200 pages)的 PDF 。此外，您可以在一天内执行 3 项任务。
在此处(here)下载此软件。在其界面上，使用所有工具(All Tools)下拉菜单，然后选择编辑(Edit)选项。这将打开其PDF 编辑器(PDF Editor)页面。
现在您可以添加PDF，它将显示该PDF的页面。在顶部，您将看到文本、链接、图像、注释、白化、形状和其他选项。使用Whiteout选项并选择PDF页面上的一个区域。它将用白色覆盖该区域。您还可以使用Shapes选项将矩形用作密文标记。
隐藏(Hide)您选择的区域，然后按保存(Save)按钮将输出PDF存储在您选择的文件夹中。
2] PDF-XChange查看器
PDF-XChange Viewer是一款实用的PDF阅读器软件，具有一些有趣的功能。它可以让您显示/隐藏书签、评论列表、测量两点之间的距离、突出显示PDF、向 PDF 添加便笺(add sticky notes to PDF)等等。它还提供了一个高亮文本工具，可用于向PDF添加修订标记。
您可以在此处(here)下载该软件的便携版或安装版。之后，打开它的界面，并添加一个PDF文件。现在，要编辑PDF，请访问突出显示文本工具(Highlight Text Tool)。它位于“工具(Tools)”菜单的“注释和标记工具(Comment and Markup Tools)”部分下。现在，单击该工具下的“显示评论样式调色板”选项。(Show Comments Styles Palette)
将打开一个单独的窗口。在那里，选择Default Style，然后使用调色板选择黑色或其他颜色。此外，使用调色板旁边的图标将不透明度设置为 100%。
再次(Again)，访问突出显示文本工具(Highlight Text Tool)。这一次，选择默认样式(Default Style)选项。现在选择某个区域，该区域将被您设置的颜色覆盖。
这样，您可以标记其他区域。最后，使用“文件”菜单下的“另存为”选项保存(Save As)PDF 。
3] AvePDF
AvePDF 服务带来了40+ tools，包括PDF转换器、压缩器、反向器、旋转器、组织器、合并器、PDF编辑器等。您最多可以上传500 MB的(500 MB) PDF文件以从中删除敏感数据。它的PDF 编辑(PDF Redact)工具允许您使用不同的颜色来添加编辑标记。
此链接(This link)将打开PDF 编辑(PDF Redact)工具页面。在那里，您可以从Google Drive(Google Drive)、桌面(desktop)或Dropbox帐户上传PDF文档。上传您的PDF文件后，它会显示PDF页面并在左侧边栏提供两个选项：添加密文标记(Add redaction marks)和应用所有密文(Apply all redactions)。
使用第一个选项，您可以选择特定页面上的区域，使用第二个选项，您可以在这些选定的区域上放置密文标记。它还在左侧边栏中显示所有密文标记的列表。默认情况下，密文标记设置为黑色。但是您可以单击一个密文标记，然后使用该特定标记的选定区域中的编辑(Edit)图标来更改其颜色。您还可以使用相同的侧边栏删除密文标记。
最后，您可以使用保存(Save)更改，然后下载编辑的PDF。
4] PDFzorro
PDFzorro是一种PDF编辑器服务，具有橡皮擦、铅笔、方框、PDF 文本荧光笔(PDF text highlighter)、方框和其他工具。您可以使用它的归档矩形工具用六种不同的颜色编辑PDF 。它的橡皮擦工具也可以用作PDF编辑器，因为它可以从PDF页面中删除您选择的区域。
访问此服务的主页(Access the homepage)，然后从 PC 或Google Drive上传(Google Drive)PDF。它还支持在线 PDF(online PDF)文件，并且没有提及上传PDF文件的任何大小限制。之后，您可以启动其PDF编辑器。
左侧边栏显示PDF页面的缩略图。当您选择缩略图时，该特定页面是可见的，其工具也是可见的。单击“(Click)修改(Modify)”选项下方的可用框以选择密文标记的颜色。之后，您可以单击矩形(Rectangle)工具，然后在PDF页面上选择一个区域。您将看到它已用所选颜色填充了该区域。这样，您可以标记其他区域。
最后，您可以使用“保存(SAVE)”按钮，并使用给定选项下载输出PDF 。该服务还允许您在其界面中预览输出PDF ，但大多数情况下无法加载PDF 。
5]小PDF
Smallpdf服务也有助于使用其编辑 PDF(Edit PDF)工具(PDF)编辑 PDF。好消息是您可以将边框颜色和背景颜色设置为编辑标记以隐藏PDF内容，或者您可以保持相同的颜色。有6种不同的颜色可供选择。
您可以使用此链接(this link)打开其PDF 编辑器(PDF Editor)工具。之后，从设备（桌面）、Dropbox或Google Drive上传(Google Drive)PDF。添加PDF后，您可以看到该PDF编辑器中的所有页面。
使用矩形(Rectangle)菜单。选择它后，您将看到两个框：一个用于背景框，另一个用于填充矩形。您可以使用这两个框的下拉菜单并选择任何可用的颜色。您应该为边框和背景设置相同的颜色。
最后，按DOWLOAD按钮将编辑的PDF保存到您的 PC。
使用高级付费软件可能仍然可以获取存储在编辑标记后面的信息，但这些PDF编辑工具可以很好地隐藏PDF内容。希望(Hope)这些对你有用。
Redact PDF using free PDF redaction software and services
PDF redaction is handy to remove or hide sensitive information from different areas of a PDF document. The selected areas are covered with redaction marks or colored boxes so that the information or data (text, links, images, etc.) stored behind it is removed permanently.
When you have to share a PDF document with someone but want to protect sensitive data of that PDF, then PDF redaction can be very useful. In this post, we have covered some best free tools to redact PDF with ease. Before using any of these tools, you should also keep a backup of your original PDF documents.
How to securely redact PDF
This post covers some free PDF redaction software and online tools to black out text in PDF:
- Sejda PDF Desktop
- PDF-XChange Viewer
- AvePDF
- PDFzorro
- Smallpdf
1] Sejda PDF Desktop
Sejda PDF Desktop is a PDF suite. Its main interface contains different tools like compress PDF, crop, merge, split, delete pages, extract pages, PDF watermark, etc. You can use its PDF Editor tool to add redaction marks in PDF pages. Instead of using black redaction marks, it provides a whiteout option to redact PDF.
This tool works well, but the free plan of this software is limited. You can add a maximum of 50 MB PDF or a PDF with up to 200 pages. Also, you can perform 3 tasks in a day.
Download this software here. On its interface, use All Tools drop-down menu, and select the Edit option. This will open its PDF Editor page.
Now you can add PDF and it will show pages of that PDF. On the top part, you will see text, links, images, annotate, whiteout, shapes, and other options. Use the Whiteout option and select an area on the PDF page. It will cover that area with white color. You can also use Shapes option to use a rectangle as redaction mark.
Hide areas of your choice and then press Save button to store the output PDF in a folder of your choice.
2] PDF-XChange Viewer
PDF-XChange Viewer is a useful PDF reader software with some interesting features. It lets you show/hide bookmarks, comments list, measure the distance between two points, highlight PDF, add sticky notes to PDF, and more. It also provides a highlight text tool that can be used to add redaction marks to PDF.
You can download a portable or installer version of this software here. After that, open its interface, and add a PDF file. Now, to redact PDF, access the Highlight Text Tool. It is present under the Comment and Markup Tools section of the Tools menu. Now, click on ‘Show Comments Styles Palette’ option under that tool.
A separate window will open. There, select Default Style, and use a color palette to select a black or some other color. Also, set the opacity level to 100% using the icon available just next to the color palette.
Again, access the Highlight Text Tool. This time, select Default Style option. Now select some area and that area will be covered with the color set by you.
In this way, you can mark other areas. Finally, save PDF using Save As option under the File menu.
3] AvePDF
AvePDF service brings 40+ tools which include PDF converters, compressor, reverser, rotator, organizer, merger, PDF redactor, etc. You can upload up to 500 MB PDF file to remove sensitive data from it. Its PDF Redact tool lets you use different colors to add redaction marks.
This link will open the PDF Redact tool page. There, you can upload a PDF document from Google Drive, desktop, or Dropbox account. After uploading your PDF file, it shows PDF pages and provides two options on the left sidebar: Add redaction marks and Apply all redactions.
Using the first option, you can select areas on a particular page, and using the second option you can put redaction marks on those selected areas. It also shows the list of all redaction marks on the left sidebar. By default, redaction marks are set to black color. But you can click on a redaction mark, and then use Edit icon in the selected area of that particular mark to change its color. You can also delete a redaction mark using the same sidebar.
Finally, you can use Save the changes and then download the redacted PDF.
4] PDFzorro
PDFzorro is a PDF editor service that has an eraser, pencil, box, PDF text highlighter, box, and other tools. You can use its filed rectangle tool to redact PDF with six different colors. Its eraser tool can also be used as a PDF redactor because it removes the area of your choice from a PDF page.
Access the homepage of this service and then upload a PDF from PC or Google Drive. It also supports online PDF files and doesn’t mention any size limit for uploading a PDF file. After that, you can start its PDF editor.
The left sidebar shows the thumbnails of PDF pages. When you select a thumbnail, that particular page is visible and its tools are also visible. Click on the box available just below the Modify option to select a color for redaction mark. After that, you can click on the Rectangle tool and then select an area on the PDF page. You will see that it has filled that area with the selected color. In this way, you can mark other areas.
Finally, you can use SAVE button, and download the output PDF using the given option. The service also lets you preview the output PDF within its interface but that fails to load PDF most of the time.
5] SmallPDF
Smallpdf service is also helpful to redact PDF using its Edit PDF tool. The good thing is you can set border color and background color as redaction marks to hide PDF content or you can keep the same color. 6 different colors are available to choose from.
You can open its PDF Editor tool using this link. After that, upload PDF from the device (desktop), Dropbox, or Google Drive. When the PDF is added, you can see all the pages in that PDF editor.
Use the Rectangle menu. As soon as you select it, you will see two boxes: one box for background and another one is for a filled rectangle. You can use drop-down menus for both the boxes and select any of the available colors. You should set the same color for the border and background.
Finally, press DOWLOAD button to save redacted PDF to your PC.
It might still be possible to fetch information stored behind redaction marks using advanced paid software, but these PDF redaction tools work well for hiding PDF content. Hope these will be useful for you.
