Mockoon vs WSO2 API Designer

Mockoon is a free, open-source tool for designing and running mock APIs locally. It supports OpenAPI and can fit into existing applications and API design workflows. Mock behavior can use dynamic templating, rule matching, JSON databases, proxy mode, webhooks, and TLS. The tool can record requests and responses from a real API to create mocks, and it supports proxying and integration testing. The open-source version permits unlimited mock APIs and routes, including parallel runs. Its CLI can run mocks in headless automated environments such as CI, GitHub Actions, and Docker; mocks can also run in serverless environments including AWS Lambda and GCP/Firebase Functions. The desktop app stores mocks locally, works offline without an account, and reports that mock content and request data are not sent to Mockoon. Pro adds real-time team collaboration, synchronized mocks, and deployment management on private infrastructure; it can be self-hosted on-premises, in a private cloud, or on isolated or air-gapped networks. Team is listed at €10 a month, billed annually at €120/license/year, tax excluded. Eligible companies can request one 14-day self-hosted Pro trial with five license slots using a verified work email, without a payment method.

WSO2 API Designer is a Visual Studio Code extension for creating and refining OpenAPI 3.x specifications in YAML or JSON. Its design view presents API resources, operations, and reusable components, with form-based editing for operations and schemas. An API Design Skill can draft specifications from prompts with GitHub Copilot; Copilot is optional. The extension checks specifications against bundled Spectral rulesets for WSO2 AI readiness, WSO2 REST API design guidelines, and the OWASP API Security Top 10. AI-assisted analysis adds narrative feedback to rule-based findings, including issues that may affect agents and tools. Users can also point it to custom rules in a GitHub folder or an absolute local directory. Installation is available through the VS Code Marketplace, with documented compatibility for extension engine requirement ^1.100.0. WSO2 directs users to its official Discord community for discussion and help. API Designer is available in a free 30-Day Trial with limits of 5 Managed Interfaces and 10M Gateway Events. Growth costs $119 a month. Enterprise pricing is custom and not listed. WSO2 warns that security checks may need real URLs, policies, or authorization-server metadata; AI should not invent production values.