Archive for the ‘Research’ Category


[Resolved] PdfSharp – invalid entry in XRef table

October 10th, 2021 / by api2pdf /

Intro If you found us through Google, welcome! Api2Pdf is a REST API that helps developers generate and interact with PDF files. Among our most popular endpoints is merging or combining PDFs together. To support the merging of PDF files, behind the scenes, our API uses the MIT-licensed PdfSharpCore library. You may be using this […]

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[Resolved] Issue downloading PDF with Java

April 8th, 2020 / by api2pdf /

We’re not java experts here, but we have gotten some reports from customers who run into issues after generating the PDF file – they want to download that file and save it locally. Never faced any issues with python or c#, but Java seems to have some problems. The below code is example of how […]

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[Resolved] PDF is rendering blank or only partially with Headless Chrome

April 8th, 2020 / by api2pdf /

Intro In this post we will outline why in some cases PDFs are rendering blank or maybe only some elements, or part of elements are appearing but not everything on the page. We are going to explain why this occurs when rendering PDFs with Headless Chrome, but it would impact any browser based engine. Common […]

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Celebrating one year and tentative roadmap for the future of the API2PDF product

June 24th, 2019 / by api2pdf /

The Past Year Hello everyone, Zack here! One year ago we hit the metaphorical GO button. It was anti-climactic of course because we had no launch strategy and Google had yet to even index our website. It was about 10 days later where I remember waking up one morning and found that a developer from […]

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Post Mortem – Ensuring High Availability on Azure Functions

June 13th, 2019 / by api2pdf /

Intro On May 15th, 2019 at 5:01 PM UTC, API2PDF services stopped generating PDF files, returning high error rates. This is what is depicted in the image above. 3 minutes later, at 5:04 PM, services resumed. While only down for 3 minutes and 99% of our customers did not even notice, at least one customer […]

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Tackling API2PDF’s technical and business challenges with Azure Table Storage and Data Lake Analytics

May 11th, 2019 / by api2pdf /

Intro Every now and then I like to post about API2PDF’s infrastructure and business side. It can be slightly more interesting than talking about PDF files. In today’s post we will combine the two by discussing our long term logging components and how we use that to track growth metrics and accounting for finance purposes. […]

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[Solved] Bootstrap striped table not printing to PDF

April 13th, 2019 / by api2pdf /

We received a support request from a developer who was using Bootstrap’s CSS and his HTML table was set to “striped” via: <table class=”table table-striped”> …</table> Now the HTML was correct, and when loading it up in a browser, the striped rows, which alternate a background color to make it easier for reading was appearing […]

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[Solved] Troubleshooting rendering issues with HTML to PDF

April 10th, 2019 / by api2pdf /

In this article we will walk you through the best way to figure out why your HTML is not properly rendering as PDF using our API service. Step 1 Open up your favorite text editor like notepad++ or VS Code and save your raw HTML that you’ve been sending to API2PDF and save it as […]

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[Resolved] Bad kerning with wkhtmltopdf rendering of html

April 4th, 2019 / by api2pdf /

Today we received an inquiry about wkhtmltopdf’s poor rendering of HTML to PDF with Google’s Roboto font. Roboto is one of the most popular fonts and so it’s important for this to be resolved. The issue with this rendering problem is known as “kerning” which means that the spacing between the fonts is incorrect. Our […]

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Multi-lingual support for HTML to PDF (wkhtmltopdf / Headless Chrome)

March 25th, 2019 / by api2pdf /

Intro – HTML to PDF with Multiple Languages A frequent question we receive at API2PDF is if it is possible to generate PDFs with foreign languages, or languages that contain special characters in their text. The answer is yes, and it is possible to support these languages in both wkhtmltopdf and Headless Chrome rendering engines. […]

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