PDF guidelines

Kivra keeps the original format and structure of PDFs sent. Kivra displays PDFs in multiple PDF viewers, leading to potential differences in appearance across platforms. It is good to note that users can also download the PDFs and view it in their own viewer.

Build accessible PDFs

Kivra accepts all types of PDFs, but strongly recommends using PDFs with PDF/UA (ISO 14289) for accessibility and compliance and PDF/A (ISO 19005) for long term preservation and archiving. Version 1.4 and later.

Structure

Organizing the structure of the PDF document is helpful for making it easier for readers to navigate through the content.

• Ensure that each element is properly tagged to represent its semantic meaning. This tagging enables assistive technology to explain the information in an accessible way.
• Make sure headings are in logical order, heading level one represents the most important heading.
• When including hyperlinks make sure to use descriptive text, avoid using phrases such as “read more”, “click here” or “link”.
• Consider adding bookmarks that help skip into specific sections of the content.

Avoid external dependencies

PDFs should be self-contained without any external dependencies (for images, fonts and so on). This is required to achieve immutability, meaning that a PDF might be accessed in Kivra several years after being created and it should look exactly as when it was created, a promise that cannot be guaranteed with external dependencies that might change or become unavailable.

Readable texts

• Text should be represented in Unicode to enable extraction. Avoid storing vectors of letters.
• In Acrobat Reader, check fonts' embedding by going to File > Properties > Fonts.
• When using multiple typefaces, consider embedding only the used characters. However, embed the entire font if few (10k-20k) characters are saved to avoid missing any.
• Avoid fonts that may be rendered by a system default replacement, as it can cause conflicts and disrupt the appearance of text in the PDF.
• Avoid CIDFontType0 encoding for European languages; it causes problems on various operating systems, browsers, and printers.
• Use Postscript, Truetype, or OpenType fonts for fewer compatibility issues.

Images

• All images should be embedded, the PDF should not rely on any external resource which might change or become inaccessible over time.
• Provide images, charts and image-based figures with alternative texts.
• Consider image dimensions: high-resolution images are meant for printing, not on screen viewing.
• Always be sure to use RGB for color-encoding over CMYK.
• Use vector format for sharper graphics at any resolution (preferably SVG).

Color & Contrast

Provide enough contrast between the text and its background. WCAG 2.2 level AA requires a contrast ratio of at least 4.5:1 for normal text and 3:1 for large text.

Metadata and language specification

Tag your content with language specifications, so screen readers can use the correct spoken language when interpreting your PDF. And if you have sections written in a different language than the rest of the document, be sure to tag them as well.

Keep in mind that Kivra also supports rich metadata that is independent of file formats. If your content represents an invoice, a calendar booking etc., we strongly recommend including that metadata so we can adapt the way we present your content to users.

Read more about the different content types we support

File Size

Check the filesize of the final PDF - many Kivra users may be looking at contents on their mobile devices with restricted bandwidth or even while traveling abroad. PDF files need to be less than 1mb in size.

Test

To guarantee PDF accessibility, it's crucial to test the user experience within Kivra's product. This includes how long it takes to load, zooming in, and even listening to the content with voice overreading the content using assistive technologies such as a screen reader. You can use our Sandbox environment to test how the PDF behaves with different types of assistive technologies.