Bitcoin Blockchain Verification

Published on November 21, 2017

Bitcoin blockchain verification

We've just added support for verifying PDFs on the Bitcoin blockchain. When you enable Bitcoin Blockchain Verification, every generated PDF will have a cryptographic proof embedded in a Bitcoin transaction. This proof verifies the integrity and existence of a PDF at the time of the transaction. You could use this feature to verify documents such as patents, wills, or contracts. Learn more about the technical details.

To celebrate the launch of this feature, we're giving away 0.0128 Bitcoins worth around $100 USD. We've created a puzzle with 10 questions, including some programming challenges. The correct result is the private key for this Bitcoin address: 1FormAP1qhonAfJToRfYZG9QtNeMFxsurL

The questions will be published on our blog on Friday, 24th November at 12:30 PM PST.
(You can visit the page now to view a countdown timer.)

HTML/CSS Templates

Published on November 15, 2017

Html css templates

FormAPI now supports HTML/CSS templates. HTML/CSS templates are great for generating documents with dynamic content, such as invoices. You can add advanced logic with Liquid, and you can style your template using SASS.

Visit the HTML/CSS Template documentation for more information.

Math Formulas

Published on October 22, 2017


We're rolling out support for formulas. You can now perform numeric calculations and display the results in your PDF. Formulas can be used for things like invoices and tax forms. Instead of writing code to run the calculations on your server, you can now push that logic into your PDF templates.

Visit the formula documentation for information about syntax, operators, and functions.

P.S. Special thanks to the awesome Dentaku library that made this feature possible. You can visit our StackShare profile to see some of the other open source software that we use.

Electronic Signatures

Published on October 13, 2017

Signature field

We've just added support for electronic signatures! You can now sign documents when you fill out our online forms. You can also sign documents via our API when you post a Base64 encoded image, or a URL where the image can be downloaded.

We've added some documentation for the Signature Field Type.

We hope you will find this feature useful. Please let us know if you need any new features, or API client libraries for a particular language.

We Launched!

Published on October 09, 2017


We made it to the front page of Hacker News and Product Hunt!

Next Steps

We received a lot of great comments and feedback, and are excited to make FormAPI even better. We will be working to improve the performance and user experience (UX) of our template editor. We'll also be listening closely to our first customers, because we want to be sure that sure we're building the right features.


One of the most common questions we received is regarding electronic signatures. We are going to add a new "Signature" type for fields, and will add a signature pad to the online form. When you generate a PDF via the API, you will need to upload a signature image. We recommend using the signature_pad library on your website.

UPDATE: We now support electronic signatures!

Thanks for all the great feedback. Please let us know if you need any features, or an API client for a specific language.