How to Check PDF Files for Errors using Node.js

A lot can go wrong within the encoding of a PDF file — especially if a threat actor wants it that way. Specially crafted PDF documents can be used to exploit vulnerabilities in PDF rendering/processing applications, and those vulnerabilities can be used to trigger denial-of-service attacks or enable remote code execution.

Thankfully, using the below code, we can take advantage of a free API that validates PDF file contents for errors and other abnormalities. We can identify password protection measures (sometimes a sign of obfuscated document errors) and otherwise ensure PDF documents strictly conform to expected PDF formatting standards.

To structure our API call, we just need to start by grabbing a free-tier API key. These allow a limit of 800 API calls per month with no commitment, so we can validate a high volume of PDF documents with minimal code at zero cost.

Then we can go about structuring our API call. We can start by installing the SDK, which involves either running the following command:

npm install cloudmersive-convert-api-client --save

Or adding the following snippet to our package.json:

  "dependencies": {
    "cloudmersive-convert-api-client": "^2.6.3"
  }

Finally, we can now call the function using the ready-to-run code examples below:

var CloudmersiveConvertApiClient = require('cloudmersive-convert-api-client');
var defaultClient = CloudmersiveConvertApiClient.ApiClient.instance;

// Configure API key authorization: Apikey
var Apikey = defaultClient.authentications['Apikey'];
Apikey.apiKey = 'YOUR API KEY';



var apiInstance = new CloudmersiveConvertApiClient.ValidateDocumentApi();

var inputFile = Buffer.from(fs.readFileSync("C:\\temp\\inputfile").buffer); // File | Input file to perform the operation on.


var callback = function(error, data, response) {
  if (error) {
    console.error(error);
  } else {
    console.log('API called successfully. Returned data: ' + data);
  }
};
apiInstance.validateDocumentPdfValidation(inputFile, callback);

That’s all there is to it — now we can easily validate PDF document uploads/downloads to avoid potential exploits.