PDF SEO covers measures that help PDF files appear in search results and display sensibly. Google lists Adobe PDF (.pdf) among the file types it can index, and it needs a parser to extract the text.
How can a PDF be optimized?
Digital.gov, a US government web team, recommends these steps for PDFs:
- a descriptive file name with hyphens between words
- text that can be searched, using OCR on scanned pages
- a unique title and a short description in the document properties
- the document language set correctly
- an HTML landing page that links to the PDF
These points are practice recommendations, not Google rules (assessment). Digital.gov also advises reducing PDFs where possible, because PDFs tend to rank below HTML pages.
A 2011 post on Google’s blog adds that Google may run OCR on text embedded as images, and that if you can copy and paste the text from a PDF, Google should be able to index it. For the title in search results, Google says it uses the title metadata in the file and the anchor text of links pointing to the PDF. These statements date from 2011.
To keep a PDF out of the index, send the HTTP header X-Robots-Tag: noindex. Google explains that a URL disallowed in robots.txt cannot have indexing rules read, so the file must stay crawlable.
Example
<Files ~ "\.pdf$">
Header set X-Robots-Tag "noindex"
</Files>
Common mistakes
Scanned PDFs without a text layer give little text to read. Content that should rank often works better as an HTML page (assessment).
Sources
- File types indexable by Google – Google Search Centraldevelopers.google.com
- Robots meta tag, data-nosnippet, and X-Robots-Tag – Google Search Centraldevelopers.google.com
- SEO for PDFs – Digital.govdigital.gov
- PDFs in Google search results – Google Search Central Blog (Sep 2011)developers.google.com
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