Best Free API Design Software of 2026

Engineered for peak performance and efficient resource use, KrakenD can manage a staggering 70k requests per second on just one instance. Its stateless build ensures hassle-free scalability, sidelining complications like database upkeep or node synchronization. In terms of features, KrakenD is a jack-of-all-trades. It accommodates multiple protocols and API standards, offering granular access control, data shaping, and caching capabilities. A standout feature is its Backend For Frontend pattern, which consolidates various API calls into a single response, simplifying client interactions. On the security front, KrakenD is OWASP-compliant and data-agnostic, streamlining regulatory adherence. Operational ease comes via its declarative setup and robust third-party tool integration. With its open-source community edition and transparent pricing model, KrakenD is the go-to API Gateway for organizations that refuse to compromise on performance or scalability.

Postman serves as a collaborative platform for developing APIs, designed to simplify the entire process of API creation and enhance teamwork, enabling the rapid development of superior APIs. The platform's features facilitate each phase of API construction, making it easier to collaborate and accelerate the creation of high-quality APIs. Users can quickly and effortlessly send requests for REST, SOAP, and GraphQL directly within Postman, optimizing their workflow. Additionally, it allows for the automation of manual tests, seamlessly integrating them into your CI/CD pipeline to safeguard against potential issues when code changes are deployed to production. API behavior can be communicated effectively by simulating endpoints and their respective responses without the need for a backend server setup. You can also generate and publish visually appealing, machine-readable documentation, which helps in making your API more accessible for users. Regular performance and response time checks ensure you stay informed about your API's health, allowing for proactive management. Lastly, Postman fosters a shared environment for API creation and consumption, enabling real-time collaboration among team members. Postman’s AI Agent Builder revolutionizes the development of AI agents with its no-code platform, enabling users to build, test, and deploy powerful agents without coding expertise. It provides access to a vast library of over 100,000 APIs and a variety of LLMs, offering tools to compare their performance, cost, and response quality. The visual workflow builder simplifies creating multi-step agent interactions, and its testing tools ensure reliability before deployment.

Tyk is an Open Source API Gateway and Management Platform that is leading in Open Source API Gateways and Management. It features an API gateway, analytics portal, dashboard, and a developer portal. Supporting REST, GraphQL, TCP and gRPC protocols We facilitate billions of transactions for thousands of innovative organisations. Tyk can be installed on-premises (Self-managed), Hybrid or fully SaaS.

Apidog provides a comprehensive suite of tools that streamlines the entire API lifecycle, empowering research and development teams to adopt optimal practices for API Design-first development. Users can design and troubleshoot APIs using a robust visual editor, paired with JSON Schema support for straightforward descriptions and debugging. The platform automates the API lifecycle through features such as test generation from API specifications, visual assertions, built-in response validation, and integration with CI/CD pipelines. Additionally, it allows for the creation of visually appealing API documentation, which can be published to a custom domain or securely shared with collaborative teams. With a local and cloud mock engine, Apidog generates realistic mock data based on field names and specifications, eliminating the need for script writing. High-quality tools are essential for fostering team collaboration while preventing redundant tasks. Users can easily describe their API during testing, generating JSON/XML schemas with just a click, and can generate test cases from APIs, visually add assertions, and create complex test scenarios with branches and iterations with remarkable ease. This seamless integration of features ensures that teams can focus on innovation rather than repetitive tasks.

One platform to build, integrate, and expose your digital services as managed APIs in cloud, on-premises and hybrid architectures to support your digital transformation strategy. Integrate with your existing identity access and key management tools to implement industry-standard authorization flows, such as OAuth Connect, OpenID Connect, or JWTs. You can create APIs using existing services, manage APIs both from third-party providers and internally built applications, and monitor their usage, performance, and retirement. To optimize your developer support, improve your services and drive adoption, you can provide real-time access API usage and performance statistics for decision-makers.

With industry-leading IBM API Connect, you can expertly secure and manage all aspects of your API ecosystem across multiple cloud platforms. This includes boosting socialization efforts and monetization efforts. IBM API Connect®, a complete, intuitive, and scalable API platform, allows you to create, securely expose and manage APIs across multiple clouds. This allows you and your customers to power digital applications and encourage innovation. IBM API Connect can also be used with other capabilities as an IBM Cloud Pak®, which can help you reach your application modernization goals in your journey to the cloud. IBM API Connect security is built using the advanced IBM(r] DataPower(r] Gateway. It comes with a single, signed and encrypted gateway that greatly reduces the risk of cybersecurity incidents. IBM API Connect has 22% market share, more than any competitor1.1 It's a trusted API solution that manages and protects services and data across multiple cloud environments.

Directus is an Open Data Platform that allows you to manage any SQL database's content. It offers a powerful API layer to developers and an intuitive app for non-technical users. Directus is written entirely in JavaScript (primarily Node.js or Vue.js), and it is modular and extensible. This allows it to be tailored to your specific project needs. Our platform can be used to manage digital experiences as a headless CMS, a database client for democratizing information, or as a standalone web app for back-office CRM, inventory, business intelligence and project management.

SyncTree strives to be a "Super Connecting Platform" that can easily connect any services you want. With SyncTree, which consists of SyncTree STUDIO, a solution for building backend business logic with block coding, and Block Store, a platform for buying and selling pre-made backend function blocks like App Store, you can organically utilize data and connect services to achieve unlimited service expansion.

Treblle is a federated API Intelligence platform that unifies API visibility, governance, and security in a single enterprise-grade solution. Designed for complex environments, Treblle connects seamlessly through one integration and supports deployment on-prem or in private cloud—meeting even the strictest regulatory and data residency requirements. Once integrated, Treblle instantly maps your entire API landscape with automatic discovery, generating real-time inventories and eliminating shadow APIs. Its observability tools track every request and response, surfacing performance issues, anomalies, and SLA breaches across all services. Advanced analytics give teams insights into traffic, latency, endpoint usage, and client behavior, making debugging, optimization, and scaling easier and 15 times faster. Security is built-in, not bolted on. Treblle provides runtime protection, threat detection, schema validation, and governance policies to safeguard APIs across environments. It empowers DevOps and platform teams to implement shift-left strategies and enforce consistent practices across the lifecycle. With its AI-powered Integration Assistant, Treblle simplifies onboarding and improves developer workflows. Whether you’re running internal microservices or customer-facing APIs, Treblle gives you the clarity and control to move faster, reduce risk, and scale with confidence.

DreamFactory is a REST API Management Platform. Auto Generate REST APIs. A cloud-based or on-premise API generation platform that is enterprise-grade. Instantly generate database APIs to build faster applications. The biggest bottleneck in modern IT is eliminated. Your project can be launched in weeks instead of months. DreamFactory creates a secure, standardized and reusable, fully documented, live REST API. DreamFactory can integrate any SQL or NoSQL file storage system or SOAP service. It instantly creates a RESTAPI with Swagger documentation, user role, and more. Every API endpoint is secured with User Management, Role Based Access Controls, SSO Authentication and Swagger documentation. Rapidly create mobile, web and IoT apps using REST-based APIs. DreamFactory offers example apps for iOS, Android and Titanium.

SwaggerHub is a comprehensive platform that integrates API design and documentation, specifically crafted for teams to maintain uniformity and discipline throughout the API development process. Enhance your team's design efficiency while preserving quality and consistent organizational style through a robust Editor that adheres to the latest Swagger (OpenAPI) specifications. This powerful Editor features intelligent error feedback and automatic syntax completion to streamline the coding process. Additionally, it includes Style Validators to maintain design uniformity across various APIs. With API Mocking, teams can simulate operations without the need for actual code. The Domains feature allows for the storage, reuse, and referencing of common OAS syntax across multiple APIs, promoting efficiency. Centralizing your API design and development in one location enables seamless collaboration among team members on new projects and easy discovery of existing APIs. Manage the entire API lifecycle through a single, centralized internal repository hosted in the cloud, which enhances accessibility and coordination among team members. By utilizing SwaggerHub, teams can significantly improve their workflow and foster innovation in API development.

Amazon API Gateway is an entirely managed service designed to simplify the process for developers to create, publish, maintain, monitor, and secure APIs, regardless of scale. Serving as the "entrance" for applications, APIs facilitate access to data, business logic, or services from the backend. Through API Gateway, developers can build both RESTful and WebSocket APIs, which are essential for enabling real-time two-way communication in applications. This service supports both containerized and serverless environments as well as web applications. It efficiently manages the complexities of processing hundreds of thousands of simultaneous API requests, handling traffic management, CORS, authorization and access control, throttling, monitoring, and versioning. Moreover, there are no upfront fees or minimum charges associated with API Gateway; instead, you only pay for the API calls and data transfer you utilize. With a tiered pricing structure, as your API usage grows, you can benefit from reduced costs, making it a cost-effective solution for businesses of all sizes. Additionally, the simplicity and scalability of API Gateway allow developers to focus more on building features rather than managing infrastructure.

Testfully offers an extensive array of features, ranging from robust API client capabilities to sophisticated testing and monitoring functionalities. Users can take advantage of versatile cloud and offline storage options, facilitate effortless collaboration among teams, and enjoy straightforward migration, all within a single, comprehensive multi-platform tool. The platform simplifies the transition of data from Postman or Insomnia, allowing for seamless integration into Testfully. With a focus on flexibility and security, users can establish global, environment, and folder variables tailored to either the workspace or individual users. The tool also allows for the customization of authentication methods, parameters, headers, and body content, making it easy to create any HTTP request. Collaboration is made simple as you can invite team members, assign specific roles, and manage folder permissions effectively. Testfully supports major authorization schemes such as OAuth2, ensuring secure and efficient access management. Whether you are dealing with straightforward tasks or more intricate scenarios, Testfully streamlines the testing process without requiring any coding skills, thus making advanced API testing more approachable and user-friendly. Users can execute requests within a folder either simultaneously, sequentially, or in a random order with a single click, enhancing efficiency. Additionally, it allows for response validation and contract testing through a declarative format, further eliminating the need for coding and simplifying the overall testing experience. Overall, Testfully is designed to cater to both novice and experienced users, ensuring that everyone can leverage its capabilities effectively.

Experience stunning API documentation that is cherished by both teams and users alike. Finally, you can create API documentation that your entire team can take pride in. In mere seconds, you can publish visually appealing API reference documents and customize them in just a few minutes. Instantly satisfy developers with essential features such as three-panel layouts, an interactive try-it console, automatically generated code snippets, SEO optimization, and an intuitive search function. Everyone knows that outdated documentation and scope creep can lead to frustration. Keep your API documentation up-to-date by integrating your preferred source control with our cloud-based workflows. Our platform is compatible with a wide range of options, including on-premise solutions and various API management systems. Set up a comprehensive developer portal within minutes by leveraging your API definitions as valuable assets. Enhance the experience with tutorials, quick-start guides, and developer tools, all while enjoying extensive customization options. Ensure your API definitions are validated, linted, and bundled seamlessly, allowing for the creation of consistently on-spec OpenAPI documents. Connect your API reference and tailor every detail to impress your API consumers, ultimately fostering a more engaging and productive environment for developers. With these capabilities, your documentation will not only serve its purpose but also become a pivotal resource for ongoing collaboration.

APIGen is an innovative AI-powered platform that allows users to swiftly design, construct, test, and launch custom APIs within minutes. By simply providing a straightforward or intricate prompt, APIGen automatically creates all the required routes, schemas, and internal functionalities, with options for adjustments as necessary. This platform utilizes a dedicated language model tailored specifically for API development, which guarantees efficient and versatile code generation. Users can seamlessly integrate their databases, connect to various third-party APIs, and take advantage of features such as code export, real-time modifications, and instant deployment to APIGen's cloud infrastructure. Additionally, APIGen takes care of authentication, session management, and security protocols for each API, offering enterprise-level protection with over 50 branches of custom tests and automatic error detection. The platform includes essential functionalities for user administration, token creation, data encryption, and generates comprehensive documentation automatically for every facet of the API. By streamlining these processes, APIGen not only enhances productivity but also simplifies the complexities often associated with API development.

WunderGraph Hub serves as a comprehensive platform that empowers development teams to collaboratively design, manage, and enhance APIs within a well-defined workflow. Acting as a unifying layer for API development, it facilitates cooperation among teams working on distributed services, enabling them to design schemas, suggest modifications, and agree on API functionalities prior to the start of implementation. The platform features a visual design canvas that allows developers, API owners, and consumers to outline capabilities, model schema architectures, and engage in discussions about requirements in a collaborative environment. After a design is established, Hub automatically creates schema proposals and collects feedback from stakeholders through controlled workflows, guaranteeing that any proposed changes to the API undergo thorough review, approval, and documentation before deployment. This method fosters a transition from casual communication and disjointed documentation to a more organized collaboration process that emphasizes clear and traceable decision-making. Ultimately, WunderGraph Hub enhances the efficiency of API development by ensuring that all team members are aligned and informed throughout the project lifecycle.

You can eliminate the need to develop back-end code. Connect to your database easily using the server address or connection string. You can customize your API methods by selecting the data you want to read, update, delete, or modify. It's done! Your front-end development team can now access your API. No back-end required. PrestoAPI supports SQL Server, MySQL and PostgreSQL. You can assign roles to users in the application or to specific projects. PrestoAPI is protected by Identity Server, OAuth 2.0 and Active Directory.

Develop an API in just half an hour and share it with your colleagues or clients, allowing them to explore the API mock without any coding required. This hands-on approach enables them to test its functionality while you refine its design—coding can be deferred until you fully understand your developers' requirements. With a focus on being developer-friendly, our API framework is robust, open source, and highly adaptable. It combines the simplicity of Markdown with the capabilities of automated mock servers, tests, validations, proxies, and code samples tailored to your preferred programming languages. Often, grasping how an API will function in real-world scenarios is challenging until you can interact with it through code. Just as wireframes serve a purpose in UI design, a server mock is essential for effective API design, providing a quick way to prototype before diving into actual coding. With only two clicks, you can connect Apiary to your selected repository, giving you the choice to keep your API Blueprint private or share it publicly for community input. Each time you commit, we refresh the API documentation, and any updates you make at Apiary are automatically pushed to your repository, creating a seamless cycle of improvement. This process not only enhances collaboration but also accelerates the overall development timeline.

A Comprehensive Solution for Developing, Testing, and Securing APIs. Revolutionize the way you create, evaluate, and oversee your APIs. Work collaboratively, execute tests locally, and safeguard sensitive information throughout the entire process. Instant Access, No Signup Required Begin using our platform immediately—eliminate the hassle of cumbersome registration or sign-in procedures. Integrations with VS Code & Desktop Applications Utilize our VS Code extension and desktop applications to ensure a smooth integration with your preferred working environment. Secure Local Storage & Execution Maintain the safety of your data through local storage and execution, which guarantees that confidential information remains on your device. Unlimited Collection Testing Effortlessly test and manage an infinite number of API collections, allowing for seamless scalability across all your initiatives. Create Mock Servers Enhance your development process by setting up mock servers that facilitate rapid testing and simulation of API responses. User-Friendly Testing & Playground Make testing easier with our intuitive interface—explore APIs without the need for any coding. Our advanced enterprise capabilities elevate your API management experience. Reach out to us for more information and to see how we can assist you further!

ApiScout serves as a comprehensive platform for the creation, evaluation, and documentation of REST APIs, boasting impressive speed without the need for waiting, restarts, or loading indicators, and is optimized for all Mac devices. You can easily craft requests and analyze responses with its user-friendly interface. As an indispensable HTTP Client tool, ApiScout streamlines the API development process, allowing you to categorize requests into organized folders for better management. Furthermore, it supports the use of dynamic values, enabling you to incorporate calculations, previous response data, environment variables, and computed hashes into your requests seamlessly. Environment variables are particularly useful for clustering related values, making it easy to switch between different user accounts or servers. By defining reusable variables such as tokens, base URLs, or credentials, you can enhance your workflow, ensuring a smooth transition between development and production environments. This level of organization and efficiency makes ApiScout an essential tool for any developer working with APIs.