Review

SDK vs API vs On-premises(Self-hosted) Deployment: What are the Differences?

By ComPDFKit | Wed. 21 May. 2025
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When businesses want to use third-party solutions to build applications or enhance product features, they typically choose from three deployment methods: SDK, API, and On-premises (Self-hosted) deployment.

 

The key difference lies in how they operate: SDKs provide tools and libraries for custom development, APIs enable interaction with external services via predefined interfaces, and On-premises deployment lets companies host the software on their own servers for greater control and security.

 

In this blog, we’ll explore their definitions, main differences, and how to choose the best option for your business.

 

sdk vs api vs on-premises deployment

 

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What are SDK, API, and On-premises(Self-hosted) Deployment

 

1. What is SDK

 

An SDK (Software Development Kit) is a set of tools and resources provided to developers to help them create, integrate, and optimize applications with specific features. Usually, an SDK includes programming libraries, API interfaces, code samples, documentation, and other development tools. Developers can use these resources to quickly build custom applications. SDKs offer high customization flexibility, allowing developers to modify and expand features based on specific business needs.

 

For example, ComPDFKit PDF SDK helps customers to render PDF with the fastest speed and offers comprehensive PDF features, such as viewing, redacting, editing, signing, converting PDF, and other customized features. Meeting enterprises’ different PDF processing needs in different scenarios.

 

sdk deployment

 

2. What is API

 

Different from SDK, API (Application Programming Interface) is a set of predefined interfaces and protocols that allow different software applications to communicate and exchange data. With an API, developers can access specific features provided by external services or systems without needing to know how they are implemented, which simplifies the integration process.

 

ComPDF's powerful online API enables developers to achieve PDF document conversion, editing, management, and watermark processing without the limitation of platforms and servers by easily RESTful API requests. This flexible extension method is suitable for connecting different systems, platforms, and servers, which allows businesses to integrate external features and services with greater efficiency.

 

api deployment

 

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3. What is On-premises (Self-hosted) Deployment

 

Unlike SDK and API, Self-hosted (On-premises) Deployment means the enterprises can install and run the software on their own servers or data centers without using external cloud services. Therefore, the enterprises have full control over the software’s environment, data storage, updates, and security. It is especially suitable for industries with high requirements for data security and compliance, such as finance, healthcare, and government. In these fields, keeping sensitive data inside the company helps reduce the risk of external security threats.

 

ComPDF Self-hosted Deployment supports processing documents securely and batchly, such as adding watermarks, extracting data from PDF documents, and other operations, with Java and .NET libraries on Linux, Windows, and MacOS. Providing businesses with stronger control and privacy protection.

 

self-hosted deployment

 

 

SDK vs API vs On-premises(Self-hosted) Deployment: What are the Differences?

 

The main differences between SDK, API, and On-premises Deployment (Self-hosted) are in where they are deployed, security, scalability, and use cases. Here is a comparison table:

 

Comparison Points

SDK

On-premises(Self-hosted) Deployment

API

Deployment Location

Client-side (local development environment / within the application)

Local servers/data centers or private cloud

Remote servers (typically hosted by the service provider)

Dependency

Depends on specific languages and platforms

Depends on the user’s infrastructure and maintenance capabilities

Web-based, usable across languages and platforms

Ease of Use

Easy to start with, includes documentation and sample code

High installation complexity, suitable for businesses with a technical team

Simple and flexible, but requires an understanding of interfaces and authentication mechanisms

Developer Control

High: Highly customizable and integrable

Very High: All configurations, data, and permissions are controlled by the user

Medium: Limited by the service provider's interface design

Security

Depends on the API and the local environment's security measures

Maximum security control, suitable for high-sensitivity data scenarios

Relies on encryption, authentication, and access control

Scalability

Scales with the client application

Limited by local resources or private cloud capabilities

High: Server-side can dynamically scale

Maintenance Burden

Low: Mostly maintained by the service provider

High: Requires independent management of deployment, updates, monitoring, etc.

Low: Only requires focus on integration and calling

Use Case

Speeds up development, builds integrated features

Full control over the software environment, data, and configurations

Real-time requests/responses, accessing remote services

Suitable Scenarios

- Rapid development

- Mobile/front-end applications

- Local integration

- High compliance requirements

- Sensitive data

- Environments with no network access restrictions

- Third-party service calls

- Microservice architecture

- Platform integration

 

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Based on the comparison table above, businesses can choose the most suitable deployment method according to their specific needs. 

 

If your company wants to quickly build an application and directly integrate third-party features, the SDK is an ideal choice. It helps businesses skip long development cycles, quickly meet user feature demands, and stay competitive in the market. 

 

If you need remote access to services and want to decouple the front-end and back-end, making it suitable for flexible calls in SaaS and mobile apps, then an API is a good choice. APIs require no complex coding or setup, and only a few lines of code are needed to make the function call. 

 

For businesses with high requirements for data sovereignty, regulatory compliance, and security, On-premises (Self-hosted) deployment is a better choice, as it provides full control over the infrastructure.

 

 

Final Words

 

In conclusion, SDK, API, and On-premises (Self-hosted) deployment each have their unique advantages. Businesses should choose the most suitable solution based on their needs and business goals. Whether you need an SDK for quick integration and customization, an API for flexibility and fast deployment, or On-premises deployment for full control over data and security, each method offers different support for your business.

 

As a professional PDF solutions provider, ComPDF offers three deployment options: local SDK, online API, and Self-hosted deployment. Whether you choose to integrate the SDK into your application, quickly connect features through our online API, or deploy the ComPDFKit Self-hosted solution on your own server, we provide tailored support to help your business improve efficiency and ensure security.

 

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