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Should You Create Your Own E-Signature API?

Zac Amos
Published: January 12, 2023

Is it worth coding your own e-signature API, or is purchasing a ready-made solution a better option? Electronic signatures have become a popular way to verify one’s identity without signing printed forms. They have many benefits over written signatures, such as higher security. 

What’s the best way to implement an API for using e-signatures: buying an API or building one? 

Benefits of E-Signatures

Electronic signatures or e-signatures have become popular over recent years as more processes go paperless. According to TechTarget, e-signatures are even legally binding in the U.S. and many other countries. 

There are many situations where it would be convenient to sign something without doing so on physical paper. For example, when filing your taxes virtually, you can use an electronic signature instead of printing paper documents. This allows you to complete your entire return digitally. Another increasingly popular use for e-signatures is in remote work, where employees can sign contracts and work-related documents without being in the office. 

Convenience isn’t the only benefit of e-signatures—they also add an extra layer of security to signed documents that written signatures can’t offer. Some types use a PIN or secondary certification method to verify that the signer is who they say they are. This would be the equivalent of hiring a notary or showing a valid ID when signing something in person. The difference is that extra layer of security is less expensive to execute than paying for a notary.

Building vs. Purchasing an E-Signature API

E-signatures can create a better experience for your team, customers, and yourself. Where do you start, though? There are plenty of web-based e-signature tools available today, but these often lack the flexibility businesses need. 

A more effective solution is an e-signature API, which can be embedded into websites and connected to different software programs, such as a business’s employee portal app. There are two main ways to obtain one. 

  1. Purchasing a ready-made version from a developer. 
  2. Building a custom API in-house. 

There are pros and cons to both options. 

Benefits of Building Your Own E-Signature API

Building a custom API in-house is the best option for many users and teams, although this is certainly not for everyone. Suppose you or a team member already have coding experience with modern programming languages, such as Python or Java. In that case, you may be able to code your own API. 

Building an API is fairly straightforward, mainly involving commands that tell the API what information to include and how to recognize it. In this case, you will need to define what a signature is, confirm that someone has correctly entered one when prompted, and how to respond to invalid entries, such as input containing numbers. You will also need to know how to code your API so it can properly integrate with other programs. 

The exact process varies depending on your chosen programming language, but Flask is the most popular tool for building APIs today. Flask is a programming framework for the Python language specifically made for building web applications. Flask and Python offer several ways to request, identify, and utilize digital signatures. 

Remember to start by importing the Flask framework in your Python program using these lines of code, courtesy of engineer James Briggs

from flask import Flask
from flask_restful import Resource, Api, reqparse

You will also need to initialize your Flask API using these two lines of code: 

app = Flask(__name__)
api = Api(app)

Next, you would create a class for the user and define a signature variable. A simple approach would be to use an if/else statement to tell the API how to respond when there is or isn’t a signature entered. For example, if you wanted the user to type in their e-signature, you could create a variable that records strings. Then you could detect an invalid blank e-signature using the len() function to measure the length of the string the user enters: 

if (len(user_signature) == 0):
  print (“Invalid signature. Please type your e-signature below: ”)
  print (“Signature accepted. Thank you!”)

Beyond this simple if/else statement, you could have your API do any number of things with the accepted signature to fit your needs. For example, you could save it to an array to call up again later or add a line in the “else” statement to tell the API to open a page or app once the signature has been accepted. 

In addition to Flask, there are many tools and plugins built for Python that can be a big help in creating an API. For example, a free tool called ImageMagick can read and write images in your API, which is helpful if you want the user to sign with their finger or mouse. This type of signature would be saved as an image rather than a string. You can use ImageMagick to convert the file format as needed, such as from SVG to PNG. 

Additionally, since Python is a popular language, you can often find code other users have written and shared to simplify your API development process. For example, this signature pad documentation plugin is already set up to request and record a user’s typed or written e-signature. You can use existing code like this as the starting point for your API and customize it to fit your exact needs.

The main benefit of taking the time to build a custom API is the ability to retain complete control over how it performs. You can ensure it’s designed to do what your team needs, such as integrating with a specific app or website. Of course, if you don’t have the in-house coding expertise, hiring someone to build a custom e-signature API could be expensive. Luckily, there’s another option. 

Benefits of Purchasing an E-Signature API

Purchasing a ready-made e-signature API is the best option for most people. It can be nice to have total control over your API functions, but most people don’t have the time or funding to build a custom version. Plenty of great e-signature APIs are already available today, so it is easy to find a ready-made one that fits your needs. 

The main benefit of purchasing an e-signature API is convenience. Coding a custom API takes time, even if you already have the personnel necessary to complete the project. Buying an e-signature API means you can use it immediately without waiting for development and testing. 

Purchasing an API is also much more cost-effective for teams that don’t have programming expertise on hand. Hiring a full-time software developer would cost thousands of dollars. According to US News, as of 2020, the median salary for a software developer was $110,140. In contrast, a typical prebuilt e-signature API would cost less than $100 per month and be ready to use immediately. 

Good developers will offer technical support, ensuring the API performs well after installation. Purchasing an API also gives you added flexibility since you can try different kinds to find one that works however you want. 


There are many benefits to using e-signatures today. An API is an efficient and effective way to use e-signatures on different applications and websites. Users must decide whether they should build their own API or buy a ready-made solution. Buying a prebuilt e-signature API is the best option for many, saving money while maximizing convenience.