API

Development

&

Consulting

For

Build secure, scalable APIs that power your business.

We specialize in developing robust, well-documented APIs that serve as the backbone of enterprise applications. Whether you're building new digital products, modernizing legacy integrations, or enabling secure access to your data, our expert developers help you design and implement APIs that are reliable, scalable, and built to last.

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API Consulting Services

We offer full lifecycle API services—design, implementation, testing, documentation, and long-term support. Our team has deep experience building APIs for web and mobile applications, third-party integrations, data pipelines, and microservices. We work with:

RESTful APIs

Clean, standardized, and scalable

GraphQL APIs

Flexible and efficient querying for modern frontends

Event-Driven APIs

Asynchronous communication for scalable, decoupled systems

Streaming APIs

Real-time data with WebSockets, Kafka, or server-sent events

gRPC APIs

High-performance APIs for internal service communication

Legacy SOAP APIs

Modernization, maintenance, or migration to REST

Why Choose Keyhole

The Keyhole Difference

Our Experts Drive Results

We deliver positive project results to our long-term clients through our highly vetted team of U.S.-based employee consultants.

100% US-based senior consultants averaging 17 years of experience

Decades of experience building enterprise integrations

Proven success across finance, healthcare, logistics, and more

We don’t just code—we architect for scale, governance, and maintainability

Whether you need to modernize legacy systems, design scalable microservices, or integrate with third-party platforms, Keyhole Software is here to help. Our expert team delivers secure, high-performance APIs tailored to your business goals.

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API Experts

We’ve helped clients integrate with hundreds of third-party systems, including:

Salesforce, Microsoft Dynamics
Stripe, Plaid, PayPal
Twilio, SendGrid
AWS, Azure, Google APIs
Custom vendor and partner systems

Trusted Partner

Trusted by nationwide clients—from Fortune 100 companies to innovative startups—across diverse industries.

Our commitment to quality keeps clients coming back: 2 out of 3 projects last year were with repeat clients.

API Technologies

Technologies and Tools That Our Team Has Used Recently

We use proven frameworks and tools to build high-performance, scalable APIs across a variety of architectures and ecosystems.

Languages & Frameworks

Our team works with modern and battle-tested languages and frameworks:

API Architecture & Tooling

We implement APIs using modern communication styles and essential tooling:

Cloud Platforms & Data

Cloud-native deployment and flexible storage backends:

DevOps, Deployment & Security

Automated pipelines and security best practices for APIs:

Observability & Monitoring

Keeping APIs reliable, performant, and visible in production:

Prometheus

Grafana

ELK Stack

Third-Party API Integration

We help clients connect with leading external platforms and tools:

Recent Client Successes

Modernizing a Legacy Mobile Application for Fuel Order Management With Flutter

[.NET & JS] Sr. Consultant Contributions at Healthcare Client

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Recent API Thought Leadership

Stay ahead with expert insights from Keyhole Software. Our team of senior engineers, architects, and consultants regularly publish in-depth articles, tutorials, and case studies covering the latest technologies, best practices, and industry trends.

Achieving Effective API Test Coverage: Best Practices and Tools

Are All Kubernetes Services in the Cloud the Same?

Navigating GCP IAP: Local and Deployed Development with .NET and React

View More Expert Insights

We've provided expertise on 150+ successful client projects

Here are some frequently asked questions our clients have had about Keyhole's API Development services.

See Our Clients

View Our Successes

We offer flexible engagement models to meet your project’s unique needs:

Software Outsourcing
Our project management + software development team builds end-to-end solutions for you.

Dedicated Dev Teams
A fully integrated, dedicated consulting team works continuously on your long-term .NET project.

Fractional & Advisory Services
Our senior software leaders provide strategic guidance to drive digital transformation.

Staff Augmentation
Our .NET developers and specialized experts join your team to accelerate development.

Whether you need a full team to build a custom application, expert consultants to integrate with your existing team, or strategic guidance to modernize a legacy system, our U.S.-based, vetted consultants provide the right expertise at the right time.

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Ready to Build Smarter APIs?

Whether you need to expose internal services, integrate with partners, or streamline your frontend development, our team is ready to help. Let’s build APIs that are secure, scalable, and built to last.