Online deployments

OCRmyPDF is designed to be used as a command line tool, but it can be used in a web service. This document describes some considerations for doing so.

A basic web service implementation is provided in the source code repository, as misc/ It is only demonstration quality and is not intended for production use.

OCRmyPDF is not designed for use as a public web service where a malicious user could upload a chosen PDF. In particular, it is not necessarily secure against PDF malware or PDFs that cause denial of service. For further discussino of security, see security.

OCRmyPDF relies on Ghostscript, and therefore, if deployed online one should be prepared to comply with Ghostscript’s Affero GPL license, and any other licenses.

Setting aside these concerns, a side effect of OCRmyPDF is that it may incidentally sanitize PDFs containing certain types of malware. It repairs the PDF with pikepdf/libqpdf, which could correct malformed PDF structures that are part of an attack. When PDF/A output is selected (the default), the input PDF is partially reconstructed by Ghostscript. When --force-ocr is used, all pages are rasterized and reconverted to PDF, which could remove malware in embedded images.

Limiting CPU usage

OCRmyPDF will attempt to use all available CPUs and storage, so executing nice ocrmypdf or limiting the number of jobs with the --jobs argument may ensure the server remains responsive. Another option would be to run OCRmyPDF jobs inside a Docker container, a virtual machine, or a cloud instance, which can impose its own limits on CPU usage and be terminated “from orbit” if it fails to complete.

Temporary storage requirements

OCRmyPDF will use a large amount of temporary storage for its work, proportional to the total number of pixels needed to rasterize the PDF. The raster image of a 8.5×11” color page at 300 DPI takes 25 MB uncompressed; OCRmyPDF saves its intermediates as PNG, but that still means it requires about 9 MB per intermediate based on average compression ratios. Multiple intermediates per page are also required, depending on the command line given. A rule of thumb would be to allow 100 MB of temporary storage per page in a file – meaning that a small cloud servers or small VM partitions should be provisioned with plenty of extra space, if say, a 500 page file might be sent.

To change the temporary directory, see Changing temporary storage location.

On Amazon Web Services or other cloud vendors, consider setting your temporary directory to empheral storage.


To prevent excessively long OCR jobs consider setting --tesseract-timeout and/or --skip-big arguments. --skip-big is particularly helpful if your PDFs include documents such as reports on standard page sizes with large images attached - often large images are not worth OCR’ing anyway.

Document management systems

If you are looking for a full document management system, consider paperless-ngx, which is a web application that uses OCRmyPDF to automatically OCR and archive documents.

Commercial OCR alternatives

The author also provides professional services that include OCR and building databases around PDFs, and is happy to provide consultation.

Abbyy Cloud OCR is viable commercial alternative with a web services API. Amazon Textract, Google Cloud Vision, and Microsoft Azure Computer Vision provide advanced OCR but have less PDF rendering capability.